bityard Blog

// IBM SVC and experiences with Real-time Compression - VMware and MS SQL Server

Following up on the previous article (IBM SVC and experiences with Real-time Compression) about our experiences with Real-time compression (RTC) in a IBM SVC environment, we did some additional and further testing with regard to RTC being used in a VMware environment hosting soley database instances of Microsoft SQL Server.

With the implementation of the seperation of all of our Microsoft SQL Server instances into an own VMware ESX cluster – which had to be done due to licensing constraints – an opportunity presented itself, to take a bit more detailed look into how well the SVCs RTC feature would perform on this particular type of workload.

Usually, the contents of a VMware datastore are by their very nature opaque to the lower levels of the storage hierarchy like the SVC which is providing the block storage for the datastores. On the one hand an advantage, this lack of transparency on the other hand also prohibits the SVC from providing a fine grained, per VM set of its usual statistics (e.g. the actual amount of storage used with thin-provisioning or RTC enabled, the amount of storage in the individual storage tier classes, etc.) and performance metrics. By not only moving the compute part of the VMs over to the new VMware ESX hosts in a seperate VMware ESX cluster, but also individually moving the storage part of one VM after the other onto new and empty datastores, which in turn were at the SVC based on newly created, empty VDisks with RTC enabled, we were able to measure the impact of RTC on a per VM level. It was a bit of tedious work and the precision of the numbers has to be taken with a grain of salt because I/O was concurrently happening on the database and operating system level, probably causing additional extends to be allocated and thus some inaccuracy to a small extent.

The environment consists of the following four datastores, four VDisks and a total number of 43 VMs running various versions of Microsoft SQL Server:

VM Datastore SVC VDisk Datastore Size (GB) Number of VMs
san-ssb-sql-oben-35C sas-4096G-35C 4096 16
san-ssb-sql-unten-360 sas-4096G-360 4096 9
san-ssb-sql-unten-361 sas-2048G-361 2048 8
san-ssb-sql-oben-362 sas-2048G-362 2048 10
Sum 12288 43

Usually the VMs are configured with one or two disks or drives for the OS and one or more disks or drives dedicated to the database contents. In some legacy cases, specifically VM #7, #10 and #12 on datastore “san-ssb-sql-oben-35C”, VM #6 on datastore “san-ssb-sql-unten-360” and VM #8 on datastore “san-ssb-sql-unten-361”, there is also a local application instance – in our case different versions of SAP – installed on the system. The operating systems used are Windows Server 2003, 2008R2 and 2012R2.

For each of the four datastores or VDisks, the results of the tests are shown in the following four sections. Each section consists of a table representation of the datastore as it was being populated with VMs in chronological order. The columns of the tables are pretty self-explainatory, with the most interesting columns being “Rel. Compressed Size”, “Rel. Compression Saving” and “Compression Ratio”. If JavaScript is enabled in your browser, click on a tables column headers to sort by that particular column. Each section also contains a graph of the absolute allocation values (table columns “VM Provisioned”, “VM Used” and “SVC Used”) per VM and a graph of the relative allocation values (values from the table column “SVC Used” divided by values from the table column “VM Used” in %) per VM. The latter ones also feature the “Compression Ratio” metric which is graphed against a second y-axis on the right-hand side of the graphs.

  • Datastore: san-ssb-sql-oben-35C
    VDisk: sas-4096G-35C

    VM VM Provisioned (GB) VM Used (GB) SVC Used (GB) SVC Delta Used (GB) Rel. Compressed Size (%) Rel. Compression Saving (%) Compression Ratio SQL Server Version Comment
    Empty Datastore 6.81 MB 6.81 MB
    Number 1 134.11 44.00 20.78 20.10 45.68 54.32 2.19 10.50.4000.0
    Number 2 144.11 55.04 48.45 28.35 51.51 48.49 1.94 11.0.5058.0
    Number 3 94.18 49.79 75.88 27.43 55.09 44.91 1.82 11.0.5058.0
    76.30 0.42
    Number 4 454.11 52.22 92.47 16.17 30.97 69.03 3.23 10.50.4000.0
    Number 5 456.11 391.14 337.74 245.27 62.71 37.29 1.59 10.50.4000.0 SharePoint with file uploads
    Number 6 238.14 156.29 450.89 113.15 72.40 27.60 1.38 10.50.6000.34 HR Applicant Management
    Number 7 488.11 304.32 660.05 209.16 68.73 31.27 1.45 10.50.4000.0 SQL Page Compression
    Number 8 348.09 259.32 703.47 43.42 16.74 83.26 5.97 9.00.4035.00
    Number 9 185.24 149.33 744.68 41.21 27.60 72.40 3.62 10.50.4000.0
    Number 10 292.12 104.31 804.14 59.46 57.00 43.00 1.75 11.0.3349.0 SQL Page Compression
    Number 11 214.11 148.73 882.44 78.30 52.65 47.35 1.90 10.50.2500.0
    Number 12 496.09 463.15 993.53 111.09 23.99 76.01 4.17 9.00.3228.00
    Number 13 202.12 176.96 1058.76 65.23 36.86 63.14 2.71 9.00.4035.00
    Number 14 442.41 363.83 1200.11 141.35 38.85 61.15 2.57 11.0.3412.0 SQL Page Compression
    Number 15 395.38 374.78 1300.00 97.96 26.14 73.86 3.83 11.0.3412.0 SQL Page Compression
    Number 16 739.31 464.30 1520.00 220.00 47.38 52.62 2.11 11.0.3412.0 SQL Page Compression
    Sum or Average 5189.63 3513.51 1497.55 42.10 57.90 2.38

    SVC RTC absolute allocation - Datastore san-ssb-sql-oben-35C; VDisk sas-4096G-35C

    SVC RTC relative allocation - Datastore san-ssb-sql-oben-35C; VDisk sas-4096G-35C

  • Datastore: san-ssb-sql-unten-360
    VDisk: sas-4096G-360

    VM VM Provisioned (GB) VM Used (GB) SVC Used (GB) SVC Delta Used (GB) Rel. Compressed Size (%) Rel. Compression Saving (%) Compression Ratio SQL Server Version Comment
    Empty Datastore 5.47 MB 5.47 MB
    Number 1 377.68 241.77 98.13 97.58 40.36 59.64 2.48 11.0.3412.0 SQL Page Compression
    Number 2 439.29 256.54 198.76 100.63 39.23 60.77 2.55 11.0.3412.0 SQL Page Compression
    Number 3 776.76 507.24 448.04 249.28 49.14 50.86 2.03 11.0.3412.0 SQL Page Compression
    Number 4 195.21 154.10 533.52 85.48 55.47 44.53 1.80 11.0.5058.0
    Number 5 34.11 23.91 546.66 13.14 54.96 45.04 1.82 9.00.4035.00
    Number 6 497.11 394.46 718.35 171.69 43.53 56.47 2.30 10.50.1702.0 SQL Page Compression
    Number 7 219.91 53.87 740.20 21.85 40.56 59.44 2.47 11.0.3000.0
    Number 8 276.11 238.67 850.77 110.57 46.33 53.67 2.16 10.50.2500.0
    Number 9 228.11 188.26 986.25 135.48 71.96 28.04 1.39 10.50.2500.0 HR Applicant Management
    Sum or Average 3044.29 2058.82 986.25 47.90 52.10 2.09

    SVC RTC absolute allocation - Datastore san-ssb-sql-unten-360; VDisk sas-4096G-360

    SVC RTC relative allocation - Datastore san-ssb-sql-unten-360; VDisk sas-4096G-360

  • Datastore: san-ssb-sql-unten-361
    VDisk: sas-2048G-361

    VM VM Provisioned (GB) VM Used (GB) SVC Used (GB) SVC Delta Used (GB) Rel. Compressed Size (%) Rel. Compression Saving (%) Compression Ratio SQL Server Version Comment
    Empty Datastore 6.66 MB 6.66 MB
    Number 1 188.11 162.98 51.46 51.45 31.57 68.43 3.17 10.50.4000.0
    Number 2 180.31 130.82 90.79 39.33 30.06 69.94 3.33 10.50.4000.0
    Number 3 178.11 142.63 131.17 40.38 28.31 71.69 3.53 10.50.4000.0
    Number 4 156.09 127.26 177.30 46.13 36.25 63.75 2.76 9.00.4035.00
    Number 5 100.86 90.40 202.76 25.46 28.16 71.84 3.55 9.00.4035.00
    205.91 3.15
    Number 6 139.09 79.17 233.85 27.94 35.29 64.71 2.83 11.0.5058.0
    Number 7 34.11 24.16 246.37 12.52 51.82 48.18 1.93 9.00.4035.00
    Number 8 696.32 289.09 402.07 155.07 53.86 46.14 1.86 11.0.5058.0 SQL Page Compression
    Sum or Average 1673.00 1046.51 402.07 38.42 61.58 2.60

    SVC RTC absolute allocation - Datastore san-ssb-sql-unten-361; VDisk sas-2048G-361

    SVC RTC relative allocation - Datastore san-ssb-sql-unten-361; VDisk sas-2048G-361

  • Datastore: san-ssb-sql-oben-362
    VDisk: sas-2048G-362

    VM VM Provisioned (GB) VM Used (GB) SVC Used (GB) SVC Delta Used (GB) Rel. Compressed Size (%) Rel. Compression Saving (%) Compression Ratio SQL Server Version Comment
    Empty Datastore
    Number 1 218.09 37.19 19.93 19.93 53.59 46.41 1.87 9.00.4035.00
    Number 2 122.12 112.53 62.32 42.39 37.67 62.33 2.65 10.50.1600.1
    Number 3 273.62 77.70 97.04 34.72 44.68 55.32 2.24 10.50.4000.0
    Number 4 143.09 37.98 116.47 19.43 51.16 48.84 1.95 11.0.5058.0
    Number 5 137.43 115.29 157.45 40.98 35.55 64.45 2.81 10.50.4000.0
    Number 6 80.09 76.04 178.76 21.31 28.02 71.98 3.57 9.00.4035.00
    182.30 3.54
    Number 7 136.09 117.59 229.95 47.65 40.52 59.48 2.47 9.00.4035.00
    Number 8 194.11 53.55 253.40 23.45 43.79 56.21 2.28 10.50.2500.0
    Number 9 78.11 52.60 273.07 19.67 37.40 62.60 2.67
    Number 10 53.11 31.42 287.33 14.26 45.39 54.61 2.20 10.50.4000.0
    Sum or Average 1435.86 711.89 283.82 40.36 59.64 2.48

    SVC RTC absolute allocation - Datastore san-ssb-sql-oben-362; VDisk sas-2048G-362

    SVC RTC relative allocation - Datastore san-ssb-sql-oben-362; VDisk sas-2048G-362

From the detailed tabular representation of each datastore on a per VM basis that is shown above, an aggregated and summarized view, shown in the table below was created. The columns of the table are again pretty self-explainatory. Some of the less interesting columns from the detailed tables above have been dropped in the aggregated result table. The most interesting columns are again “Rel. Compressed Size”, “Rel. Compression Saving” and “Compression Ratio”. Again, if JavaScript is enabled in your browser, click on a tables column headers to sort by that particular column.

VM Datastore SVC VDisk VM Provisioned (GB) VM Used (GB) SVC Used (GB) Rel. Compressed Size (%) Rel. Compression Saving (%) Compression Ratio
san-ssb-sql-oben-35C sas-4096G-35C 5189.63 3513.51 1497.55 42.10 57.90 2.38
san-ssb-sql-unten-360 sas-4096G-360 3044.29 2058.82 986.25 47.90 52.10 2.09
san-ssb-sql-unten-361 sas-2048G-361 976.68 757.42 243.21 32.53 67.47 3.07
san-ssb-sql-oben-362 sas-2048G-362 1435.86 711.89 283.82 40.36 59.64 2.48
Sum or Average 10646.46 7041.64 3010.83 42.76 57.24 2.34

On the whole, the compression results achived with RTC at SVC level are quite good. Considering the fact that VMware already achieved a sizeable amount of storage reduction through its own thin-provisioning algorithms, the average RTC compression ratio of 2.34 – with a minimum of 1.38 and a maximum of 5.97 – at the SVC is even more impressive. This means that on average only 42.76% of the storage space allocated by VMware is actually used on the SVC level to store the data. Taking VMware thin-provisioning into account, the relative amount of actual storage space needed sinks even further down to 28.28%, or in other words a reduction by a factor of 3.54.

Looking at the individual graphs offers several other interesting insights, which can be indicators for further investigations on the database layer. In the graphs showing the relative allocation values and titled “SVC Real-Time Compression Relative Storage Allocation and Compression Ratio on VMware with MS SQL Server”, those data samples with a high “Rel. Compressed Size” value (purple bars) or a low “Compression Ratio” value (red line) are of particular interest in this case. Selecting those systems from the above results, with an – arbitrarily choosen – value of well below 2.00 for the “Compression Ratio” metric, gives us the following list of systems to take a closer look at:

Sample Datastore / VDisk VM # VM Provisioned (GB) VM Used (GB) SVC Delta Used (GB) Compression Ratio Comment
1 san-ssb-sql-oben-35C sas-4096G-35C 3 94.18 49.79 27.43 1.82 SQLIO benchmark file
2 5 456.11 391.14 245.27 1.59 SharePoint with file uploads
3 6 238.14 156.29 113.15 1.38 HR Applicant Management
4 7 488.11 304.32 209.16 1.45 SAP and MSSQL (with SQL Page Compression) on the same VM
5 10 292.12 104.31 59.46 1.75 SAP and MSSQL (with SQL Page Compression) on the same VM
6 san-ssb-sql-unten-360 sas-4096G-360 4 195.21 154.10 85.48 1.80 SQLIO benchmark file
7 5 34.11 23.91 13.14 1.82
8 9 228.11 188.26 135.48 1.39 HR Applicant Management
9 san-ssb-sql-unten-361 sas-2048G-361 7 34.11 24.16 12.52 1.93
10 8 696.32 289.09 155.07 1.86 SAP and MSSQL (with SQL Page Compression) on the same VM
11 san-ssb-sql-oben-362 sas-2048G-362 1 218.09 37.19 19.93 1.87
12 4 143.09 37.98 19.43 1.95

The reasons for why those particular systems are exhibiting a subaverage compression ratio could be manifold. Together with our DBAs we went over the list and came up with the following, not exhaustive nor exclusive list of explainations which are already hinted in the “Comment” columns of the above table:

  • Samples 1 and 6: Those systems were recently used to test the influence of 4k vs. 64k NTFS cluster size on the database I/O performance. Over the course of these tests, a number of dummy files were written with the SQLIO benchmark tool. Altough the dummy files were deleted after the tests were concluded, the storage blocks remained allocated with apparently less compressible contents.

  • Samples 2, 3 and 8: Those systems host the databases for SharePoint (sample #2) and a HR/HCM applicant management and employee training management system (samples #3 and #8). Both applications seem to be designed or configured to store files uploaded to the application as binary blobs into the database. Both usecases suggest that the uploaded file data is to some extent already in some kind of compressed format (e.g. xlsx, pptx, jpeg, png, mpeg, etc.), thus limiting the efficiency of any further compression attempt like RTC. Storing large amounts of unstructured data together with structured data in a database is subject of frequent, ongoing and probably never ending, controversial discussions. There are several points of view to this question and good arguments are being made from either side. Personally and from a purely operational point of view, i'd favour the unstructured binary data not to be stored in a structured database.

  • Sample 4: This system hosts the legacy design described above, where a local application instance of SAP is installed along Microsoft SQL Server on the same system. The database tables of this SAP release already use the SQL Server page compression feature. Although this could have very well been the cause for the subaverage compression ratio, a look into the OS offered a different plausible explanation. Inside the OS the sum of space allocated to the various filesystems is only approximately 202 GB, while at same time the amount of space allocated by VMware is a little more than 304 GB. It seems that at one point in time there was a lot more data of unknown compressibility present on the system. The data has since been deleted, but the previously allocated storage blocks have not been properly reclaimed.

    In order to put this theory to test, the procedure described in VMware KB 2004155 to reclaim the unused, but not de-allocated storage blocks, was applied. The following table shows the storage allocation for the system in sample #4 before and after the reclaim procedure:

    Sample Datastore / VDisk VM # VM Provisioned (GB) VM Used (GB) SVC Delta Used (GB) Compression Ratio Comment
    4 san-rtc-ssb-sql-unten-366 sas-1024G-366 7 488.11 304.32 209.16 1.45 SAP and MSSQL (with SQL Page Compression) on the same VM - before reclaiming unused storage space
    4 7 488.11 172.53 81.29 2.12 SAP and MSSQL (with SQL Page Compression) on the same VM - after reclaiming unused storage space

    The numbers show that the above assumption was correct. After zeroing unused disk space within the VM and reclaiming unused storage blocks by re-thin-provisioning the virtual disks in VMware, the RTC compression ratio rose from a meager 1.45 to a near average 2.12. Now, only 47.11% – instead of the previous 68.73% – of the storage space allocated by VMware is actually used on the SVC level. Again, taking VMware thin-provisioning into account, the relative amount of actual storage space needed sinks even further down to 16.65%, or in other words a reduction by a factor of 6.00.

  • Samples 5 and 10: These systems basically share the same circumstances as the previously examined system in sample #4. The only difference is, that there is still some old, probably unused data sitting in the filesystems. In case of sample #5 it's about 20 GB of compressed SAP installation media and in case of sample #10 it's about 84.3 GB of partially compressed SAP installation media and SAP SUM update files. Of course we'd like to also reclaim this storage space and – hopefully – in the course of this some deleted, but up to now not de-allocated storage blocks, too. By this we hope to see equally good end results as in the case of sample #4. We're currently waiting on clearance from our SAP team to dispose of some of the old and probably unused data.

  • Samples 7, 9, 11 and 12: Systems in this sample category are probably best described as just being “small”. To better illustrate what is meant by this, the following table shows a compiled view of these four samples. The data was taken from the detailed tabular representation of each datastore on a per VM basis that is shown above:

    Sample Datastore / VDisk VM # VM Provisioned (GB) VM Used (GB) SVC Delta Used (GB) Rel. Compressed Size (%) Rel. Compression Saving (%) Compression Ratio Windows Version
    7 san-ssb-sql-unten-360 sas-4096G-360 5 34.11 23.91 13.14 54.96 45.04 1.82 2003
    9 san-ssb-sql-unten-361 sas-2048G-361 7 34.11 24.16 12.52 51.82 48.18 1.93 2003
    11 san-ssb-sql-oben-362 sas-2048G-362 1 218.09 37.19 19.93 53.59 46.41 1.87 2012 R2
    12 4 143.09 37.98 19.43 51.16 48.84 1.95 2012 R2

    Inside the systems there is very little user or installation data besides the base Windows operating system, the SQL Server binaries and some standard management tools which are used in our environment. VMware thin-provisioning already does a significant amount of space reduction. It reduces the storage space that would be used on the SVC level to approximately 24 GB for Windows 2003 and approximately 37.5 GB for Windows 2012 R2 systems. Although the number of samples is rather low, the almost consistent values within each Windows release category suggest that these values represent – in our environment – the minimal amount of storage space needed for each Windows release. The compressed size of approximately 12.8 GB for Windows 2003 and approximately 19.7 GB for Windows 2012 R2 systems as well as the average compression ratio of approximately 1.89 seem to support this theory in the way that they show very similar values within each Windows release category. It appears that – in our environment – these values are the bottom line with regard to minimal allocated storage capacity. There simply seems not to be enough other data with a good compressability in those systems in order to achieve better results with regard to the overall compression ratio.

By and large, we're quite pleased with the results we're seeing from the SVCs real-time compression feature in our VMware and MS SQL server environment. The amount of storage space saved is – especially with VMware thin-provisioning taken into account – significant. Even in those cases where the SQL servers page compression feature is heavily used, we're still seeing quite good compression results with the use of the additional real-time compression at the SVC level. In part, this is very likely due to the fact that real-time compression at the SVC level also covers the VMs data that is outside of the scope which is covered by the SQL servers page compression. On the other hand, this does not entirely suffice to explain the amount of saved storage space – between 50.86% and 73.86%, if we disregard some special cases for which the reasons of a low compression ratio were discussed above – we're seeing in cases where SQL server page compression is used. From the data collected and shown above, it would appear that the algorithms used in SQL server page compression still leave enough redundant data of low entropy for the algorithms used in the RACE at the SVC level to perform rather well.

In general and with regard to performance in particular we have – up to now – not noticed any negative side effects, like e.g. noticeable increases in I/O latency, by using RTC for the various SQL server and SAP systems shown above.

The use of RTC not only promises, but quite matter of factly offers a significant reduction of the storage space needed. Even with seemingly already compressed workloads, like e.g. SQL server page compressed databases, it deals very well. It thus enables a delayed procurement of additional storage resources, lower operational costs (administration, rack space, power, cooling, etc.), a reduced amount of I/O to the backend storage systems and a more efficient use of tier-1 storage like e.g. flash based storage systems.

It is on the other hand also no out-of-the-box, fire-and-forget solution when used sensibly. The selected examples of “interesting” systems, which were shown and discussed above, illustrates very well that there are always usecases which require special attention. They also point out the increased necessity of a good overall, interdisciplinary technical knowledge or a very good and open communication between the organisational units responsible for application, database, operating system, virtualization and storage administration.

Due to the rather old release level of our VMware environment we unfortunately weren't able to cover the interaction of TRIM, UNMAP, VAAI and RTC. It'd be very interesting to see if and how well those storage block reclaimation technologies work together with the SVCs real-time compression feature.

Comments and own experiences are – as always – very welcome!

// IBM SVC and experiences with Real-time Compression

We've been using the IBM SAN Volume Controller (SVC) for several years now (since about 2006). While the technological progress was a tad slow in the early years, development – probably along with popularity and more widespread use – of the SVC fortunately picked up considerable pace in recent years. For us the most interesting new features that emerged over time are the:

  • stretched cluster configuration, which seems to be far more popular in europe with its traditionally shorter distances between datacenters. It allows us to provide active-active access to host LUNs and thus considerably simplifying a resilient VMware environment.

  • synchronous VDisk mirroring, which allows us to provide mirrored LUNs that are independent of the storage vendor in the backend.

  • EasyTier, which allows us to utilize our TMS RamSan (now IBM Flash System) flash storage much more efficiently.

  • Real-time compression (RTC), which as well allows us to utilize our overall backend storage much more efficiently.

We also went through several cycles of node hardware, starting with our initial 2145-4F2 via the 2145-8F2 and the 2145-8G4 to our current 2145-CG8. Currently our overall environment looks like this:

  • Six 2145-CG8 nodes in three I/O groups.

  • A stretched cluster configuration covering two datacenters which are within a distance of about 300 meters of single-mode fibre length. A quorum storage on a third location on the same campus.

  • Dual fabric 8GB FC SAN consisting of four Brocade DCX-4S directors.

  • A total of six disk based storage systems from different vendors (HDS AMS2300, Fujitsu DX90, IBM V3700), one of each vendor in each datacenter, with a total capacity of about 260TB. The systems are typically sized and configured for multiple 4+1 or 8+1 RAID-5 arrays. The arrays are subsequently mapped entirely as LUNs to the SVC. All the LUNs from one disk storage system are pooled together into one MDiskGroup, forming a single, striped failure group.

  • A total of six flash based storage systems (TMS RamSan-630, TMS RamSan-810, IBM Flashsystem 820), one of each model in each datacenter, with a total capacity of about 34TB. The systems LUNs are also mapped to the SVC and all the LUNs from one flash storage are added to one disk based MDiskGroup for use as a SSD tier with EasyTier.

  • 65 host systems (IBM xSeries, IBM BladeCenter and IBM Power), running either non-virtualized or virtualized (VMware, Xen, PowerVM) workloads.

  • 291 VDisks, ranging from sizes of 1GB up to 4TB. Almost all VDisks are mirrored, exceptions are made where the application on the host prefers to do the mirroring or the replication itself (e.g. MS Exchange).

For about seven months – since the end of april 2014 – we've now been using Real-time compression (RTC). We started by implementing RPQ 8S1296 on all of our nodes. This added an additional 6-core CPU and 24GB memory to each node. As a result the “normal” SVC operation still uses four of the CPU-cores on the initially installed CPU and the RTC algorithm is dedicated eight CPU-cores – two on the initially and six on the additionally installed CPU. The SVC code version was v7.1.0.3 when we initially started testing and implementing RTC (see the screenshots below). After gradually converting more and more VDisks to compressed volumes, the CPU load of the RTC algorithm became quite noticable (30-60%). Along with that, a substancially increased latency (>10ms) could be observed. After updating the SVC code to v7.2.0.7, the CPU utilization dropped noticably to 10% and below. The latency also went back to the values (<2ms) usually observed before implementing RTC. There must have been quite an improvement in the RTC code, unfortunately IBM does not publish any such interesting details.

Over the course of implementing RTC, i took four series of screenshots from the SVC WebUI showing the compression allocation view at that particular point in time. They have been combined into the four following images showing all information at once, with the last one being a representation of the current situation:

RTC compressed capacity - Sample 1

RTC compressed capacity - Sample 2

RTC compressed capacity - Sample 3

RTC compressed capacity - Sample 4

One thing about the visual representation in the compression allocation view and the volume of RTC licensed storage – which confused me too at first – has to be noted. It seems that with regard to RTC licensing only the storage space allocated to primary VDisk volumes i.e. the unmirrored storage capacity is considered. From the information available on the matter at the time, both the corresponding sections from the “IBM EMEA Software Announcement ZP12-0235”:

The license entitles users for the quantity of terabytes of SVC volumes created with real-time compression enabled. The volume size (and not necessarily the amount of data you are able to store on that volume compressed) is the measure used to determine how many terabytes of 5641-CP1 to license.

and from the “Real-time Compression in SAN Volume Controller and Storwize V7000” redpaper:

In SAN Volume Controller, real-time compression is licensed by the total number of terabytes of virtual capacity, which is the amount of storage that the host sees.

are a bit ambiguous. At first the emphasis seems to be on the matter of uncompressed vs. compressed storage size. But on second thought, the key words “[…] the amount of storage that the host sees.” from the second quote come into play. Those basically say, that enabling RTC on secondary VDisk copies is free, since a host only sees the unmirrored amount of storage.

Example: In our setup each VDisk compressed with RTC has also a secondary copy, also compressed with RTC. There is currently only one exception in the form of a flash copy volume of 2750GB which is compressed, but not mirrored. The currently compressed virtual capacity is 62.67TB. The currently used RTC licenses is being reported as 32.68TB. The calculation is: ( 62.67TB - 2750GB ) / 2 + 2750GB = 32.68TB. Makes sense, doesn't it?

For the four cases shown in the images above, the average RTC+TP and RTC-only compression ratio, relative storage size after compression and relative storage saving have been calculated and are shown in the following table:

Sample RTC plus Thin Provisioning RTC only
Ratio Relative Size Relative Saving Ratio Relative Size Relative Saving
1 1:3.75 26.69% 73.31% 1:3.06 32.65% 67.35%
2 1:3.63 27.51% 72.49% 1:3.02 33.07% 66.92%
3 1:3.5 28.58% 71.42% 1:2.80 35.65% 64.35%
4 1:3.2 31.25% 68.75% 1:2.60 38.53% 61.47%

Although thin provisioning (TP) alone would amount to 16-20% storage saving on the overall average, the larger and quiet substancial effect of 64-67% of storage saving on the overall average can only be achieved with RTC. Needless to say, we're currently only using RTC on VDisks that promise to yield rather good compression results. This is done in order to save valueable licensed compression volume and to minimize the number of CPU cycles wasted on uncompressible data. For guidelines please see the recommendations in the redbook referenced below in the “Links & Resources” section. The VDisks have either been chosen by estimating the compressability with the comprestimator utility or by knowing the application data very well. VDisks which contain data with an inherent high entropy, like e.g. encrypted and compressed MS Exchange DAGs, repositories of already compressed installation media, compressed Windows system images or compressed AIX mksysb images, page compressed MS SQL data files or fileserver volumes with user data (docx, xlsx, pptx, zip, jpeg, mpeg, etc.) have been excluded from RTC for now. We're still investigating which way to ultimately go on the topic of MS SQL page compression vs. IBM SVC RTC. We're also still sorting out the “mess” of compressible and uncompressible data being mixed together within the same VMware datastores before converting some of them into RTC enabled VDisks. We'll probably end up with a mix of RTC enabled VDisks backing VMware datastores containing compression-friendly VMs and regular VDisks backing datastores containing high-entropy, less compressible VMs. It'll be interesting to see what the ratio between the two will be and which VM will fall into which category.

A detailed compilation of storage saving with RTC on a per VDisk basis is shown in the section Detailed per VDisk RTC data. The columns are pretty self-explainatory, with the most interesting columns being “Application Type”, “Size (%)” and “Saving (%)”. To get a better overview, a condensed view aggregated by “Application Type” was compliled. The following table shows the values aggregated by “Application Type”. The columns “Avg. Size (GB)” and “Avg. Compressed Size (GB)” show the arithmetic average for the VDisk size and compressed size. To be able to compare the different application types against each other, relative arithmetic averages were calculated (columns “Avg. Size (%)” and “vg. Saving (%)”). The columns “Min./Max. Size/Saving (%)” and “Samples” are provided to get an impression about the variability and the significance of the arithmetic averages.

Application Type Avg. Size (GB) Avg. Compressed Size (GB) Min. Size (%) Avg. Size (%) Max. Size (%) Min. Saving (%) Avg. Saving (%) Max. Saving (%) Samples
AIX rootvg 16.61 5.53 9.38 33.29 73.44 9.38 66.71 90.62 198
Apache & MySQL 19.56 10.58 17.19 54.12 84.38 15.62 45.88 82.81 18
Code Server 200.00 64.50 32.25 32.25 32.25 67.75 67.75 67.75 2
Fileserver 350.00 142.63 40.71 40.75 40.79 59.21 59.25 59.29 2
Linux Package 250.00 152.75 61.10 61.10 61.10 38.90 38.90 38.90 2
MS SQL 120.00 18.50 15.42 15.42 15.42 84.58 84.58 84.58 2
Database 346.40 86.56 5.38 24.99 59.17 40.83 75.01 94.62 80
ERP 426.95 141.02 21.25 33.03 48.05 51.95 66.97 78.75 59
TSM OpCenter 26.00 9.25 35.58 35.58 35.58 64.42 64.42 64.42 2
VMware ESX 1756.00 798.84 28.34 45.49 53.73 46.27 54.51 71.66 8
Windows Package 300.00 185.13 61.67 61.71 61.75 38.25 38.29 38.33 2
Xen Server 512.00 184.64 11.87 36.06 47.75 52.25 63.94 88.13 18

A graphical representation of the above aggregated data is shown in the following graph:

Relative average SVC RTC VDisk size by application

The values “Avg. Size (%)” and “Avg. Saving (%)” are shown as colored bars, the error bars are their respective relative minimum and maximum values, the numbers at the bottom of the colored bars are the number of samples per application type.

The “AIX rootvg” and “Database” application types show rather good compression results, but also a high range of variability. For the case of “AIX rootvg” the compression results depend mainly on the amount of paging space being used, since on all systems the paging space is part of the rootvg. Systems with very low compressed VDisk size also show no or almost no paging space usage. For the case of “Database” the compression results obviously depend on the data stored within the database tablespaces, unfortunately i have no further information on what kind of data is stored in the less compressible cases. In the most compressible cases (5.38% and 7.32% of the original VDisk size) though, the databases contain large amounts of text data and fulltext search indexes, which explains the extraordinary compression results. The “ERP” application type shows equally good compression results, but with a much lower variability, which seems to be largely caused by the current amount of free unused database space. The sample from the “MS SQL” application type is unfortunately the only VDisk directly allocated to a MS SQL Server instance, so it's not really a representative sample. All other MS SQL Server instance in our environment run on VMware and the VDisks there are currently not RTC enabled due to the application and use case mixture described above. The “Code Server” and “Fileserver” application types show good compression results, considering the data usually associated with those. The low sample number indicated that they have specifically been chosen as candidates for RTC enabled VDisks. Especially the other available fileserver VDisks showed much worse results in the preliminary comprestimator runs. Only the the fileserver VDisk containing the Windows server saved user profiles showed good enough results to justify enabling RTC. The “Linux Package” and “Windows Package” application types show the expected worst compression results, since the data on those VDisks is already stored in compressed formats. Still, compression savings of approximately 40% on this kind of data is still pretty good. The “Apache & MySQL” application type is by its compression behaviour kind of a mixture between the “AIX rootvg” and “Fileserver” application types, since it has the same paging space configuration and has large amounts of already compressed data (bz2, gz, docx, xlsx, pptx, zip, jpeg, mpeg, etc.) stored on the VDisks. The “VMware ESX” and “Xen Server” also show average compression results, considering that those are run by 3rd parties where there is currently no distinction between and seperation of compression-friendly from compression-unfriendly VM data being made.

Overall, we're up to now quite happy with the SVCs RTC feature, since it gives us some breathing room and on the overall takes off the pressure to evaluate, purchase, implement and maintain additional storage units for the foreseeable future. On the downside, there is a pretty hefty price tag to the RTC volume licenses. Especially compared to other vendors (e.g. Pure Storage) where the compression functionality is part of the systems base package. One is advised to do a thorough TCO calculation to determine whether the investment in SVC RTC licenses outways the benefits of operating storage systems with actually allocateable space. In the end this boils down to a bet about the current and future compressability of the data actually stored. Besides licensing terms another issue for us was, that we unfortunately pretty quickly reached the limit for the allowed number of compressed VDisks per I/O group on our current 2145-CG8 hardware (max. 200 RTC enabled VDisks). This limit is put in place by SVC development as a safeguard, supposedly in order to keep the nodes from being overloaded with RTC workload. While understandable from a technical point of view, this limit can be reached pretty quickly if you're for example using a lot RTC enabled rootvgs or if you're following the SAP or Oracle disk layout guidelines pretty closely. For the rootvgs and possibly test and development SAP or Oracle systems a consolidation of the system and data disks into fewer VDisks using AIX/VIOS shared storage pools could be an option. But then again, the same downsides for e.g. VMware datastores apply to shared storage pools as well.

Detailed per VDisk RTC data

Detailed compilation of storage saving with RTC on a per VDisk basis. If JavaScript is enabled in your browser, click on a column headers to sort by that particular column.

Application Type VDisk Name Type Size (GB) Compressed Size (GB) Size (%) Saving (%) Ext. HDD Ext. SSD
AIX rootvg sas-8G-197 primary 8.00 4.00 50.00 50.00 16 0
AIX rootvg sas-8G-197 secondary 8.00 4.00 50.00 50.00 16 0
AIX rootvg sas-24G-155 primary 24.00 8.50 35.42 64.58 34 0
AIX rootvg sas-24G-155 secondary 24.00 8.50 35.42 64.58 34 0
AIX rootvg sas-16G-209 primary 16.00 4.00 25.00 75.00 16 0
AIX rootvg sas-16G-209 secondary 16.00 4.00 25.00 75.00 16 0
AIX rootvg sas-16G-2CA primary 16.00 2.50 15.62 84.38 10 0
AIX rootvg sas-16G-2CA secondary 16.00 2.50 15.62 84.38 10 0
AIX rootvg sas-16G-2C8 primary 16.00 2.75 17.19 82.81 11 0
AIX rootvg sas-16G-2C8 secondary 16.00 2.75 17.19 82.81 11 0
AIX rootvg sas-16G-2C9 primary 16.00 2.50 15.62 84.38 10 0
AIX rootvg sas-16G-2C9 secondary 16.00 2.50 15.62 84.38 10 0
AIX rootvg sas-16G-23E primary 16.00 2.50 15.62 84.38 10 0
AIX rootvg sas-16G-23E secondary 16.00 2.50 15.62 84.38 10 0
AIX rootvg sas-16G-2B5 primary 16.00 1.50 9.38 90.62 6 0
AIX rootvg sas-16G-2B5 secondary 16.00 1.50 9.38 90.62 6 0
AIX rootvg sas-16G-307 primary 16.00 11.75 73.44 26.56 47 0
AIX rootvg sas-16G-307 secondary 16.00 11.75 73.44 26.56 47 0
AIX rootvg sas-16G-2AA primary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-2AA secondary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-8G-19A primary 8.00 1.50 18.75 81.25 6 0
AIX rootvg sas-8G-19A secondary 8.00 1.50 18.75 81.25 6 0
AIX rootvg sas-8G-241 primary 8.00 1.75 21.88 78.12 7 0
AIX rootvg sas-8G-241 secondary 8.00 1.75 21.88 78.12 7 0
AIX rootvg sas-8G-2BD primary 8.00 1.50 18.75 81.25 6 0
AIX rootvg sas-8G-2BD secondary 8.00 1.50 18.75 81.25 6 0
AIX rootvg sas-8G-2BE primary 8.00 1.50 18.75 81.25 6 0
AIX rootvg sas-8G-2BE secondary 8.00 1.50 18.75 81.25 6 0
AIX rootvg sas-8G-194 primary 8.00 1.25 15.62 84.38 5 0
AIX rootvg sas-8G-194 secondary 8.00 1.25 15.62 84.38 5 0
AIX rootvg sas-8G-195 primary 8.00 1.50 18.75 81.25 6 0
AIX rootvg sas-8G-195 secondary 8.00 1.50 18.75 81.25 6 0
AIX rootvg sas-8G-22F primary 8.00 3.75 46.88 53.12 15 0
AIX rootvg sas-8G-22F secondary 8.00 3.75 46.88 53.12 15 0
AIX rootvg sas-16G-264 primary 16.00 6.00 37.50 62.50 24 0
AIX rootvg sas-16G-264 secondary 16.00 6.00 37.50 62.50 24 0
AIX rootvg sas-16G-263 primary 16.00 7.00 43.75 56.25 28 0
AIX rootvg sas-16G-263 secondary 16.00 7.00 43.75 56.25 28 0
AIX rootvg sas-16G-1D2 primary 16.00 7.00 43.75 56.25 0 28
AIX rootvg sas-16G-1D2 secondary 16.00 7.00 43.75 56.25 28 0
AIX rootvg sas-16G-1B1 primary 16.00 5.50 34.38 65.62 0 22
AIX rootvg sas-16G-1B1 secondary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-16G-14D primary 16.00 5.75 35.94 64.06 0 23
AIX rootvg sas-16G-14D secondary 16.00 5.75 35.94 64.06 23 0
AIX rootvg sas-32G-322 primary 32.00 8.50 26.56 73.44 34 0
AIX rootvg sas-32G-322 secondary 32.00 8.50 26.56 73.44 34 0
AIX rootvg flash-32G-1F3 primary 32.00 11.75 36.72 63.28 0 47
AIX rootvg flash-32G-1F3 secondary 32.00 11.75 36.72 63.28 47 0
AIX rootvg sas-16G-1F1 primary 16.00 7.50 46.88 53.12 0 30
AIX rootvg sas-16G-1F1 secondary 16.00 7.50 46.88 53.12 30 0
AIX rootvg sas-16G-15C primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-15C secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-32G-1F4 primary 32.00 8.25 25.78 74.22 33 0
AIX rootvg sas-32G-1F4 secondary 32.00 8.25 25.78 74.22 33 0
AIX rootvg sas-16G-267 primary 16.00 5.25 32.81 67.19 21 0
AIX rootvg sas-16G-267 secondary 16.00 5.25 32.81 67.19 21 0
AIX rootvg sas-16G-2F4 primary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-16G-2F4 secondary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-16G-2FB primary 16.00 8.75 54.69 45.31 35 0
AIX rootvg sas-16G-2FB secondary 16.00 8.75 54.69 45.31 35 0
AIX rootvg sas-16G-11F primary 16.00 7.00 43.75 56.25 28 0
AIX rootvg sas-16G-11F secondary 16.00 7.00 43.75 56.25 28 0
AIX rootvg sas-16G-265 primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-265 secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-146 primary 16.00 6.25 39.06 60.94 25 0
AIX rootvg sas-16G-146 secondary 16.00 6.25 39.06 60.94 25 0
AIX rootvg sas-16G-28C primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-28C secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-28E primary 16.00 9.75 60.94 39.06 39 0
AIX rootvg sas-16G-28E secondary 16.00 9.75 60.94 39.06 39 0
AIX rootvg sas-16G-205 primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-205 secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-1BD primary 16.00 10.00 62.50 37.50 40 0
AIX rootvg sas-16G-1BD secondary 16.00 10.00 62.50 37.50 40 0
AIX rootvg sas-16G-28F primary 16.00 10.25 64.06 35.94 41 0
AIX rootvg sas-16G-28F secondary 16.00 10.25 64.06 35.94 41 0
AIX rootvg sas-16G-162 primary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-162 secondary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-2A9 primary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-2A9 secondary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-1B9 primary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-1B9 secondary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-1BA primary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-1BA secondary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-1BC primary 16.00 9.75 60.94 39.06 39 0
AIX rootvg sas-16G-1BC secondary 16.00 9.75 60.94 39.06 39 0
AIX rootvg sas-16G-1BB primary 16.00 11.50 71.88 28.12 46 0
AIX rootvg sas-16G-1BB secondary 16.00 11.50 71.88 28.12 46 0
AIX rootvg sas-16G-1A9 primary 16.00 3.50 21.88 78.12 14 0
AIX rootvg sas-16G-1A9 secondary 16.00 3.50 21.88 78.12 14 0
AIX rootvg sas-16G-2CE primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-2CE secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-29B primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-29B secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-1BF primary 16.00 8.25 51.56 48.44 33 0
AIX rootvg sas-16G-1BF secondary 16.00 8.25 51.56 48.44 33 0
AIX rootvg sas-16G-243 primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-243 secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-2CF primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-2CF secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-29C primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-29C secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-242 primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-242 secondary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-29E primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-29E secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-2D0 primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-2D0 secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-29D primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-29D secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-1BE primary 16.00 8.25 51.56 48.44 33 0
AIX rootvg sas-16G-1BE secondary 16.00 8.25 51.56 48.44 33 0
AIX rootvg sas-16G-29F primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-29F secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-261 primary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-16G-261 secondary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-8G-199 primary 8.00 1.25 15.62 84.38 5 0
AIX rootvg sas-8G-199 secondary 8.00 1.25 15.62 84.38 5 0
AIX rootvg sas-8G-240 primary 8.00 3.00 37.50 62.50 12 0
AIX rootvg sas-8G-240 secondary 8.00 3.00 37.50 62.50 12 0
AIX rootvg sas-16G-249 primary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-249 secondary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-24G-15D primary 24.00 5.00 20.83 79.17 20 0
AIX rootvg sas-24G-15D secondary 24.00 5.00 20.83 79.17 20 0
AIX rootvg sas-16G-24B primary 16.00 4.25 26.56 73.44 17 0
AIX rootvg sas-16G-24B secondary 16.00 4.25 26.56 73.44 17 0
AIX rootvg sas-16G-24D primary 16.00 6.00 37.50 62.50 24 0
AIX rootvg sas-16G-24D secondary 16.00 6.00 37.50 62.50 24 0
AIX rootvg sas-16G-252 primary 16.00 5.25 32.81 67.19 21 0
AIX rootvg sas-16G-252 secondary 16.00 5.25 32.81 67.19 21 0
AIX rootvg sas-16G-278 primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-278 secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-279 primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-279 secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-270 primary 16.00 5.25 32.81 67.19 21 0
AIX rootvg sas-16G-270 secondary 16.00 5.25 32.81 67.19 21 0
AIX rootvg sas-16G-284 primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-284 secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-285 primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-285 secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-27A primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-27A secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-2DC primary 16.00 6.25 39.06 60.94 25 0
AIX rootvg sas-16G-2DC secondary 16.00 6.25 39.06 60.94 25 0
AIX rootvg sas-16G-27B primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-27B secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-310 primary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-310 secondary 16.00 4.75 29.69 70.31 19 0
AIX rootvg sas-16G-312 primary 16.00 10.00 62.50 37.50 40 0
AIX rootvg sas-16G-312 secondary 16.00 10.00 62.50 37.50 40 0
AIX rootvg sas-36G-22B primary 36.00 9.00 25.00 75.00 36 0
AIX rootvg sas-36G-22B secondary 36.00 9.00 25.00 75.00 36 0
AIX rootvg sas-16G-22D primary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-22D secondary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-308 primary 16.00 6.75 42.19 57.81 23 4
AIX rootvg sas-16G-308 secondary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-233 primary 16.00 8.75 54.69 45.31 35 0
AIX rootvg sas-16G-233 secondary 16.00 8.75 54.69 45.31 35 0
AIX rootvg sas-16G-30A primary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-30A secondary 16.00 6.75 42.19 57.81 27 0
AIX rootvg sas-16G-226 primary 16.00 6.00 37.50 62.50 24 0
AIX rootvg sas-16G-226 secondary 16.00 6.00 37.50 62.50 24 0
AIX rootvg sas-16G-0F1 primary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-16G-0F1 secondary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-24G-1A4 primary 24.00 7.50 31.25 68.75 30 0
AIX rootvg sas-24G-1A4 secondary 24.00 7.50 31.25 68.75 30 0
AIX rootvg sas-16G-1AE primary 16.00 4.50 28.12 71.88 17 1
AIX rootvg sas-16G-1AE secondary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-24G-1A5 primary 24.00 9.75 40.62 59.38 39 0
AIX rootvg sas-24G-1A5 secondary 24.00 9.75 40.62 59.38 39 0
AIX rootvg sas-24G-1A6 primary 24.00 8.75 36.46 63.54 35 0
AIX rootvg sas-24G-1A6 secondary 24.00 8.75 36.46 63.54 35 0
AIX rootvg sas-16G-259 primary 16.00 3.25 20.31 79.69 13 0
AIX rootvg sas-16G-259 secondary 16.00 3.25 20.31 79.69 13 0
AIX rootvg sas-16G-19E primary 16.00 2.75 17.19 82.81 11 0
AIX rootvg sas-16G-19E secondary 16.00 2.75 17.19 82.81 11 0
AIX rootvg sas-24G-257 primary 24.00 4.50 18.75 81.25 18 0
AIX rootvg sas-24G-257 secondary 24.00 4.50 18.75 81.25 18 0
AIX rootvg sas-16G-343 primary 16.00 2.00 12.50 87.50 8 0
AIX rootvg sas-16G-343 secondary 16.00 2.00 12.50 87.50 8 0
AIX rootvg sas-16G-212 primary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-212 secondary 16.00 5.00 31.25 68.75 20 0
AIX rootvg sas-16G-214 primary 16.00 4.00 25.00 75.00 16 0
AIX rootvg sas-16G-214 secondary 16.00 4.00 25.00 75.00 16 0
AIX rootvg sas-16G-213 primary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-213 secondary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-1E7 primary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-16G-1E7 secondary 16.00 5.50 34.38 65.62 22 0
AIX rootvg sas-24G-1E0 primary 24.00 3.75 15.62 84.38 15 0
AIX rootvg sas-24G-1E0 secondary 24.00 3.50 14.58 85.42 14 0
AIX rootvg sas-16G-1E2 primary 16.00 4.25 26.56 73.44 17 0
AIX rootvg sas-16G-1E2 secondary 16.00 4.25 26.56 73.44 17 0
AIX rootvg sas-24G-305 primary 24.00 7.00 29.17 70.83 21 7
AIX rootvg sas-24G-305 secondary 24.00 7.00 29.17 70.83 28 0
AIX rootvg sas-24G-306 primary 24.00 6.75 28.12 71.88 22 5
AIX rootvg sas-24G-306 secondary 24.00 6.75 28.12 71.88 27 0
AIX rootvg sas-16G-323 primary 16.00 4.50 28.12 71.88 18 0
AIX rootvg sas-16G-323 secondary 16.00 4.50 28.12 71.88 18 0
Apache & MySQL sas-16G-13A primary 16.00 7.75 48.44 51.56 24 7
Apache & MySQL sas-16G-13A secondary 16.00 7.75 48.44 51.56 31 0
Apache & MySQL sas-16G-18D primary 16.00 9.75 60.94 39.06 38 1
Apache & MySQL sas-16G-18D secondary 16.00 9.75 60.94 39.06 39 0
Apache & MySQL sas-16G-303 primary 16.00 11.00 68.75 31.25 44 0
Apache & MySQL sas-16G-303 secondary 16.00 11.00 68.75 31.25 44 0
Apache & MySQL sas-16G-2C3 primary 16.00 13.50 84.38 15.62 45 9
Apache & MySQL sas-16G-2C3 secondary 16.00 13.50 84.38 15.62 54 0
Apache & MySQL sas-32G-2C1 primary 32.00 17.50 54.69 45.31 33 37
Apache & MySQL sas-32G-2C1 secondary 32.00 17.50 54.69 45.31 70 0
Apache & MySQL sas-32G-2C2 primary 32.00 18.00 56.25 43.75 36 36
Apache & MySQL sas-32G-2C2 secondary 32.00 18.00 56.25 43.75 72 0
Apache & MySQL sas-16G-2D8 primary 16.00 2.75 17.19 82.81 8 3
Apache & MySQL sas-16G-2D8 secondary 16.00 2.75 17.19 82.81 11 0
Apache & MySQL sas-16G-2D9 primary 16.00 4.75 29.69 70.31 16 3
Apache & MySQL sas-16G-2D9 secondary 16.00 4.75 29.69 70.31 19 0
Apache & MySQL sas-16G-304 primary 16.00 10.25 64.06 35.94 33 8
Apache & MySQL sas-16G-304 secondary 16.00 10.25 64.06 35.94 41 0
Code Server sas-200G-17E primary 200.00 64.50 32.25 67.75 202 56
Code Server sas-200G-17E secondary 200.00 64.50 32.25 67.75 258 0
Fileserver sas-350G-1D5 primary 350.00 142.50 40.71 59.29 351 219
Fileserver sas-350G-1D5 secondary 350.00 142.75 40.79 59.21 571 0
Linux Package sas-250G-23C primary 250.00 152.75 61.10 38.90 468 143
Linux Package sas-250G-23C secondary 250.00 152.75 61.10 38.90 611 0
MS SQL flash-120G-10A primary 120.00 18.50 15.42 84.58 0 74
MS SQL flash-120G-10A secondary 120.00 18.50 15.42 84.58 74 0
Database sas-100G-1F8 primary 100.00 23.75 23.75 76.25 82 13
Database sas-100G-1F8 secondary 100.00 23.75 23.75 76.25 95 0
Database sas-100G-2CD primary 100.00 12.00 12.00 88.00 31 17
Database sas-100G-2CD secondary 100.00 12.00 12.00 88.00 48 0
Database sas-100G-2CB primary 100.00 14.50 14.50 85.50 45 13
Database sas-100G-2CB secondary 100.00 14.50 14.50 85.50 58 0
Database sas-100G-2CC primary 100.00 11.25 11.25 88.75 31 14
Database sas-100G-2CC secondary 100.00 11.25 11.25 88.75 45 0
Database flash-150G-23F primary 150.00 30.25 20.17 79.83 0 121
Database flash-150G-23F secondary 150.00 30.25 20.17 79.83 121 0
Database sas-150G-30E primary 150.00 88.75 59.17 40.83 297 58
Database sas-150G-30E secondary 150.00 88.75 59.17 40.83 355 0
Database sas-600G-30D primary 600.00 104.75 17.46 82.54 108 311
Database sas-600G-30D secondary 600.00 105.00 17.50 82.50 420 0
Database sas-150G-32D primary 150.00 19.00 12.67 87.33 45 31
Database sas-150G-32D secondary 150.00 19.00 12.67 87.33 76 0
Database sas-600G-32C primary 600.00 107.75 17.96 82.04 54 377
Database sas-600G-32C secondary 600.00 107.75 17.96 82.04 431 0
Database sas-120G-147 primary 120.00 49.25 41.04 58.96 167 30
Database sas-120G-147 secondary 120.00 49.25 41.04 58.96 197 0
Database sas-170G-28D primary 170.00 52.75 31.03 68.97 88 123
Database sas-170G-28D secondary 170.00 52.75 31.03 68.97 211 0
Database sas-300G-290 primary 300.00 97.00 32.33 67.67 315 73
Database sas-300G-290 secondary 300.00 97.00 32.33 67.67 388 0
Database sas-1550G-1C6 primary 1550.00 355.25 22.92 77.08 119 1302
Database sas-1550G-1C6 secondary 1550.00 355.25 22.92 77.08 1421 0
Database sas-150G-1C8 primary 150.00 31.25 20.83 79.17 45 80
Database sas-150G-1C8 secondary 150.00 31.25 20.83 79.17 125 0
Database sas-100G-291 primary 100.00 26.75 26.75 73.25 100 7
Database sas-100G-291 secondary 100.00 26.75 26.75 73.25 107 0
Database sas-900G-296 primary 900.00 309.75 34.42 65.58 123 1116
Database sas-900G-296 secondary 900.00 309.50 34.39 65.61 1238 0
Database sas-1000G-2AD primary 1000.00 73.25 7.32 92.67 283 10
Database sas-1000G-2AD secondary 1000.00 73.25 7.32 92.67 293 0
Database sas-1300G-1C2 primary 1300.00 299.50 23.04 76.96 185 1013
Database sas-1300G-1C2 secondary 1300.00 299.50 23.04 76.96 1198 0
Database sas-2150G-294 primary 2150.00 660.50 30.72 69.28 206 2436
Database sas-2150G-294 secondary 2150.00 660.75 30.73 69.27 2643 0
Database sas-150G-297 primary 150.00 44.50 29.67 70.33 73 105
Database sas-150G-297 secondary 150.00 44.50 29.67 70.33 178 0
Database sas-600G-1C5 primary 600.00 167.00 27.83 72.17 373 295
Database sas-600G-1C5 secondary 600.00 167.25 27.88 72.12 669 0
Database sas-200G-24A primary 200.00 52.00 26.00 74.00 120 88
Database sas-200G-24A secondary 200.00 52.00 26.00 74.00 208 0
Database flash-160G-24C primary 160.00 74.75 46.72 53.28 0 299
Database flash-160G-24C secondary 160.00 74.75 46.72 53.28 299 0
Database flash-260G-24E primary 260.00 74.25 28.56 71.44 0 297
Database flash-260G-24E secondary 260.00 74.25 28.56 71.44 297 0
Database sas-120G-253 primary 120.00 31.50 26.25 73.75 28 98
Database sas-120G-253 secondary 120.00 31.25 26.04 73.96 125 0
Database sas-250G-27C primary 250.00 53.00 21.20 78.80 157 55
Database sas-250G-27C secondary 250.00 53.00 21.20 78.80 212 0
Database flash-350G-27D primary 350.00 79.75 22.79 77.21 0 319
Database flash-350G-27D secondary 350.00 79.75 22.79 77.21 319 0
Database sas-180G-271 primary 180.00 51.75 28.75 71.25 98 109
Database sas-180G-271 secondary 180.00 52.00 28.89 71.11 208 0
Database sas-260G-286 primary 260.00 56.75 21.83 78.17 51 176
Database sas-260G-286 secondary 260.00 56.75 21.83 78.17 227 0
Database flash-150G-287 primary 150.00 34.25 22.83 77.17 0 137
Database flash-150G-287 secondary 150.00 34.25 22.83 77.17 137 0
Database sas-180G-27E primary 180.00 39.75 22.08 77.92 144 15
Database sas-180G-27E secondary 180.00 39.75 22.08 77.92 159 0
Database sas-180G-2DD primary 180.00 50.25 27.92 72.08 143 58
Database sas-180G-2DD secondary 180.00 50.25 27.92 72.08 201 0
Database flash-180G-27F primary 180.00 43.50 24.17 75.83 0 174
Database flash-180G-27F secondary 180.00 43.75 24.31 75.69 175 0
Database sas-120G-311 primary 120.00 36.50 30.42 69.58 85 61
Database sas-120G-311 secondary 120.00 36.50 30.42 69.58 146 0
Database flash-120G-313 primary 120.00 47.00 39.17 60.83 0 188
Database flash-120G-313 secondary 120.00 47.00 39.17 60.83 188 0
Database sas-140G-22A primary 140.00 49.50 35.36 64.64 80 118
Database sas-140G-22A secondary 140.00 49.75 35.54 64.46 199 0
Database sas-150G-22C primary 150.00 62.00 41.33 58.67 246 2
Database sas-150G-22C secondary 150.00 62.00 41.33 58.67 248 0
Database sas-80G-309 primary 80.00 17.75 22.19 77.81 47 24
Database sas-80G-309 secondary 80.00 17.75 22.19 77.81 71 0
Database sas-36G-30B primary 36.00 18.00 50.00 50.00 72 0
Database sas-36G-30B secondary 36.00 18.00 50.00 50.00 72 0
Database sas-200G-344 primary 200.00 10.75 5.38 94.62 43 0
Database sas-200G-344 secondary 200.00 10.75 5.38 94.62 43 0
ERP sas-250G-2C6 primary 250.00 76.50 30.60 69.40 110 196
ERP sas-250G-2C6 secondary 250.00 76.50 30.60 69.40 306 0
ERP sas-250G-10E primary 250.00 77.50 31.00 69.00 110 200
ERP sas-250G-10E secondary 250.00 77.50 31.00 69.00 310 0
ERP sas-2750G-345 primary 2750.00 803.50 29.22 70.78 3214 0
ERP flash-2750G-1B5 primary 2750.00 803.75 29.23 70.77 0 3215
ERP flash-2750G-1B5 secondary 2750.00 803.50 29.22 70.78 3214 0
ERP sas-150G-2D1 primary 150.00 41.25 27.50 72.50 126 39
ERP sas-150G-2D1 secondary 150.00 41.25 27.50 72.50 165 0
ERP sas-100G-2A0 primary 100.00 27.75 27.75 72.25 92 19
ERP sas-100G-2A0 secondary 100.00 27.75 27.75 72.25 111 0
ERP sas-130G-2A3 primary 130.00 53.00 40.77 59.23 77 135
ERP sas-130G-2A3 secondary 130.00 53.00 40.77 59.23 212 0
ERP sas-300G-2A6 primary 300.00 63.75 21.25 78.75 183 72
ERP sas-300G-2A6 secondary 300.00 63.75 21.25 78.75 255 0
ERP sas-150G-2D2 primary 150.00 38.50 25.67 74.33 98 56
ERP sas-150G-2D2 secondary 150.00 38.50 25.67 74.33 154 0
ERP sas-200G-2A1 primary 200.00 61.50 30.75 69.25 228 18
ERP sas-200G-2A1 secondary 200.00 61.25 30.63 69.38 245 0
ERP sas-250G-2A4 primary 250.00 108.00 43.20 56.80 60 372
ERP sas-250G-2A4 secondary 250.00 108.00 43.20 56.80 432 0
ERP sas-450G-2A7 primary 450.00 151.75 33.72 66.28 325 282
ERP sas-450G-2A7 secondary 450.00 151.75 33.72 66.28 607 0
ERP sas-700G-2D3 primary 700.00 228.00 32.57 67.43 61 851
ERP sas-700G-2D3 secondary 700.00 228.00 32.57 67.43 912 0
ERP sas-650G-2A2 primary 650.00 278.50 42.85 57.15 94 1020
ERP sas-650G-2A2 secondary 650.00 278.50 42.85 57.15 1114 0
ERP sas-320G-2A5 primary 320.00 153.75 48.05 51.95 69 546
ERP sas-320G-2A5 secondary 320.00 153.75 48.05 51.95 615 0
ERP sas-550G-2A8 primary 550.00 207.25 37.68 62.32 634 195
ERP sas-550G-2A8 secondary 550.00 207.50 37.73 62.27 830 0
ERP sas-340G-248 primary 340.00 87.00 25.59 74.41 340 8
ERP sas-340G-248 secondary 340.00 87.00 25.59 74.41 348 0
ERP sas-270G-2D4 primary 270.00 87.00 32.22 67.78 72 276
ERP sas-270G-2D4 secondary 270.00 86.75 32.13 67.87 347 0
ERP sas-340G-1AF primary 340.00 79.50 23.38 76.62 318 0
ERP sas-340G-1AF secondary 340.00 79.50 23.38 76.62 318 0
ERP sas-300G-2D5 primary 300.00 80.25 26.75 73.25 66 255
ERP sas-300G-2D5 secondary 300.00 80.25 26.75 73.25 321 0
ERP flash-370G-2D6 primary 370.00 118.50 32.03 67.97 0 474
ERP flash-370G-2D6 secondary 370.00 118.50 32.03 67.97 474 0
ERP sas-80G-101 primary 80.00 34.25 42.81 57.19 114 23
ERP sas-80G-101 secondary 80.00 34.25 42.81 57.19 137 0
ERP sas-260G-2E8 primary 260.00 90.00 34.62 65.38 310 50
ERP sas-260G-2E8 secondary 260.00 90.00 34.62 65.38 360 0
ERP sas-430G-11B primary 430.00 184.75 42.97 57.03 510 229
ERP sas-430G-11B secondary 430.00 184.75 42.97 57.03 739 0
ERP sas-460G-1D4 primary 460.00 179.75 39.08 60.92 669 50
ERP sas-460G-1D4 secondary 460.00 179.75 39.08 60.92 719 0
ERP sas-520G-236 primary 520.00 199.50 38.37 61.63 331 467
ERP sas-520G-236 secondary 520.00 199.50 38.37 61.63 798 0
ERP sas-170G-180 primary 170.00 62.00 36.47 63.53 204 44
ERP sas-170G-180 secondary 170.00 62.00 36.47 63.53 248 0
ERP sas-100G-14A primary 100.00 35.50 35.50 64.50 139 3
ERP sas-100G-14A secondary 100.00 35.50 35.50 64.50 142 0
ERP sas-210G-25B primary 210.00 84.75 40.36 59.64 157 182
ERP sas-210G-25B secondary 210.00 84.75 40.36 59.64 339 0
ERP sas-170G-22E primary 170.00 65.00 38.24 61.76 133 127
ERP sas-170G-22E secondary 170.00 65.00 38.24 61.76 260 0
TSM OpCenter sas-26G-301 primary 26.00 9.25 35.58 64.42 37 0
TSM OpCenter sas-26G-301 secondary 26.00 9.25 35.58 64.42 37 0
VMware ESX sas-1024G-1A7 primary 1024.00 290.25 28.34 71.66 1161 0
VMware ESX sas-1024G-1A7 secondary 1024.00 290.25 28.34 71.66 1161 0
VMware ESX sas-2000G-172 primary 2000.00 1030.75 51.54 48.46 2268 1855
VMware ESX sas-2000G-172 secondary 2000.00 1030.75 51.54 48.46 4123 0
VMware ESX sas-2000G-222 primary 2000.00 1074.50 53.73 46.27 2940 1358
VMware ESX sas-2000G-222 secondary 2000.00 1074.50 53.73 46.27 4298 0
VMware ESX sas-2000G-2B1 primary 2000.00 800.00 40.00 60.00 2632 568
VMware ESX sas-2000G-2B1 secondary 2000.00 799.75 39.99 60.01 3199 0
Windows Package sas-300G-1B8 primary 300.00 185.25 61.75 38.25 552 189
Windows Package sas-300G-1B8 secondary 300.00 185.00 61.67 38.33 740 0
Xen Server sas-512G-1AC primary 512.00 244.50 47.75 52.25 975 3
Xen Server sas-512G-1AC secondary 512.00 238.50 46.58 53.42 954 0
Xen Server sas-512G-1AD primary 512.00 212.25 41.46 58.54 750 99
Xen Server sas-512G-1AD secondary 512.00 206.75 40.38 59.62 827 0
Xen Server sas-512G-26D primary 512.00 175.50 34.28 65.72 661 41
Xen Server sas-512G-26D secondary 512.00 170.50 33.30 66.70 682 0
Xen Server sas-512G-283 primary 512.00 242.25 47.31 52.69 848 121
Xen Server sas-512G-283 secondary 512.00 238.75 46.63 53.37 955 0
Xen Server sas-512G-2B2 primary 512.00 147.75 28.86 71.14 12 579
Xen Server sas-512G-2B2 secondary 512.00 141.50 27.64 72.36 566 0
Xen Server sas-512G-2D7 primary 512.00 221.00 43.16 56.84 35 849
Xen Server sas-512G-2D7 secondary 512.00 219.50 42.87 57.13 878 0
Xen Server sas-512G-2E9 primary 512.00 151.25 29.54 70.46 600 5
Xen Server sas-512G-2E9 secondary 512.00 146.50 28.61 71.39 586 0
Xen Server sas-512G-332 primary 512.00 61.75 12.06 87.94 245 2
Xen Server sas-512G-332 secondary 512.00 60.75 11.87 88.13 243 0
Xen Server sas-512G-341 primary 512.00 225.50 44.04 55.96 854 48
Xen Server sas-512G-341 secondary 512.00 219.00 42.77 57.23 876 0
This website uses cookies for visitor traffic analysis. By using the website, you agree with storing the cookies on your computer.More information