MSA 2000 Expand vdisk performance

[Alan Saxon_1]

Compared with the MSA1000/MSA1500 the MSA2000 seems very slow in this area. Firstly you can only add 4 discs at a time but then it takes for ever to expand. I have a RAID 5 set of 3 x 300 Gb that I added 4 discs to and after 48 hours it is only 48% complete. This implies it will take 100hrs to expand. Utility performance is set at HIGH which seems to be the default.
I am worried about rebuild times after a disc failure which I cannot now test for another 52 hours.

[TTr]

Keep in mind that the LUN expansion is much more involved that a single disk rebuild.

Going from 3 to 7 disks in RAID5, enough stripe data has to be loaded in to the MSA controller memory, then deleted from the 3 old disks, and then split into a 7 pieces and written out to 7 disks. And this is done for 900GB of data.

In a case of a disk rebuild for your 7 disk raid5, six disks would be read from and only one disk would be written to. I am guessing that it would be faster than that.

When you say the utility performance is set to high, is this the LUN rebuild rate?

[Alan Saxon_1]

I am comparing this with an MSA1000 where to do the same thing would be considerably faster and is not limited to just 4 disc expansion. This is the single controller base model, maybe the other controller is faster at this process. But I guess I have live with that. Will test the rebuild.

Performance selection does not seem to be very granular, manual says "You can change verify, reconstruct, Expand and Initialize utilities ...." so it lumps them all together as far as I can tell.

In our case there is no I/O activity so there is no competition.