Compression on SVC and Storwize V7000
talor 27000411MV Comment (1) Visits (5004)
Recently IBM have introduced compression into the SVC and V7000 storage systems for block volumes.
Our business runs on V7000, so we updated it to 6.4 code (required for compression) and I had a play around with it today.
Compression is a licensed feature, and in a V7000 is licensed per tray of disk in your V7000.
There are two ways to use it:
1. Create a new compressed volume.
2. Add a compressed copy to an existing volume, and then remove the original non-compressed copy.
To create a non-compressed volume, is easy, here is how. What's better is that i'm using external storage to compress my volume, so now our DS5020 is taking advantage of the compression!
The other way is to add a mirrored copy which is compressed, change the primary volume to be the compressed volume, then delete the old copy.
Here is is on the command line:
Now, how about the space savings? The compression feature can give up to 80% space saving with no performance penalty. Obviously there would be an overhead when mirroring to a compressed copy, but once you are at the end state, there will be no overhead.
Lets have a look.
So that's 50% saving. Some data ie databases will compress more than others. So it's telling me that i've used 132.84 of real data, after 49% compression? Lets have a closer look:
capacity 134.00GB <---
used_capacity 135.16MB <---
compressed_copy yes <---
Lastly, what about CPU overhead on my node canisters? This is something that needs to be monitored, as the compression processing, may add some CPU overhead. Once I've had the chance to play around with it more, I'll post my findings here. See below, there is an additional metric in the performance monitor, so you can see what CPU your compression is using. In my case none, however the workload on our V7000 is pretty minimal, and I've only compressed a few volumes. Overall though, this feature works awesome.
Update... One of my colleges tried it out on an iSeries LPAR using VIO and a V7000. To me these are those other "weird" LPARs that run on Power Systems that aren't AIX.
Typically iSeries data compresses very well, so we tried out compression on a couple volumes. We are getting 87% compression which is unbelievable. One other good feature, is that we can see compression savings across the whole V7000 storage pool. See below.