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“Almost Free” Capacity With Storwize V7000 Real-Time Compression


The IBM Storwize family of products offers a feature called Real-time Compression (RTC). IBM acquired the technology (and the company Storwize) in 2010. The technology is patent protected and unique in that it compresses data in-line without slowing things down. (Caveat: there must be ample CPU/memory resources available to do compression.) RTC was initially implemented as an appliance to place in front of Network-Attached Storage (NAS) filers (NetApp or Nseries) and would compress NAS data on the fly before getting to the NAS appliance.

IBM has since implemented the technology into its Storwize family of products for fixed block storage. The SAN Volume Controller (SVC) and Storwize V7000 offer an RTC option

So how do you get almost free capacity? The following scenario describes capitalizing on the RTC feature of the V7000 to reduce your capital costs of disk.

“Almost Free” Capacity

Let’s say your business requirement was 50 TB useable capacity of 300GB/15K disks. To yield that, the Storwize V7000 configuration will be almost 9 full drawers with 24 disks each and will look something like Figure 1.

In this example, we’ll use approximate IBM list price figures. The cost is about $600,000 for hardware and V7000 software. (Disclaimer: IBM U.S. list prices are approximate from IBM U.S. announcement letters.)

If we utilize compression and apply a conservative 50-percent compression reduction rate, the hardware is reduced by 50 percent so we’ll only need 4.5 disk drawers. That configuration will now look like Figure 2.

We’ll need less V7000 software as well but will be adding compression software. The resulting solution is half the physical capacity (25 TB) plus RTC; using 50-percent compression will yield the same 50 TB of useable capacity as previous but at a cost of about $375,000.

That’s 35-percent less capital for the same capacity (or more if compression is better than 50 percent). Again, we reduced the V7000 hardware/software cost by almost 50 percent but added cost for compression software.

To approach it from another angle, let’s assume we’ve already purchased a V7000 with 50 TB of useable capacity for about $600,000. We’re running out of space and need another 50 TB for a new application, but our budget is limited. By adding the compression feature, we may at least double useable capacity to 100 TB or more. The cost of V7000 compression software is definitely not another $600,000; it’s less than seven percent of that figure.

In this case, we’ve doubled the useable capacity to 100 TB or more for less than seven percent of the original cost. Note that three is the maximum number of required RTC licenses per V7000 controller.

How Will My Data Compress?

If you want to know how your data will compress, IBM provides a utility called “Comprestimator” that will analyze your specific data volumes and predict the expected compression savings. The predictions are very accurate since the tool analyzes your data and applies the same compression algorithms as RTC.

If you’re still skeptical about compression, start with the standard 50 TB (or smaller) disk configuration and try compression before you buy. IBM allows a 45-day compression test allowance. When compression proves beneficial, it will enable your company to delay future capacity upgrades for the nominal cost of RTC software.

Reduce Cost

RTC on the Storwize V7000 can be used for primary production data (databases, email, etc.) and greatly reduces cost of block disk storage.

Compression is also available on SVC, which enables compression for any vendors’ disk supported by the SVC. The vendor list is very large.

If you have a NAS filer like the IBM Nseries, remember that there is a RTC appliance for this environment with the same compression benefits for file servers. The RTC appliance also works with NetApp, Fujitsu and EMC filers.

Ed Chaves is a solution architect at Forsythe Technology Inc. Ed provides support to storage solution architects, product specialists and account managers.



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