MSA1000 disk reconfiguration

[Gavin Strudley_1]

In the beginning I had;
ServerA attached to MSA1000 with a single shelf
ServerB attached through Smart Array 5302 to 4314 shelf,
ServerC attached through SA 5302 to 4314 shelf.

Using the documented procedure, I migrated the 4314 shelves onto the MSA1000 and used SSP so that;
ServerA uses its original disks in Shelf0
ServerB uses its original disks in Shelf1
ServerC uses its original disks in Shelf2.

Now I need to improve the resilience by moving the disks across shelves so that a single shelf failure will not cause a server to fail, e.g. loss of Shelf2 causes failure of ServerC.

Is there a documented procedure for this? Has anybody tried it?

[Jefferson Humber]

Gavin,

I was under the impression that the physical position of the HDD's was not important, since all the array information was stored on the RIS partition of each disk....and the SmartArray controller was clever enough to work things out itself.

When you perform a DtS migration they even say in the guide that the drive order is not important.

ftp://ftp.compaq.com/pub/products/storageworks/msa1000/NT_Win2K_DtS_Migrations.pdf

However I have never done this with my MSA, so can't say for certain.

Has anybody else ever tried this ?

[Uwe Zessin · Accepted solution]

Yes, I have tried it and it worked, almost. There was one disk drive that did not get proper contact to the backplane and ran into an error. After putting the disk back into the original slot, the rebuilt went fine.

I had to swap disks around multiple times as I wanted to keep the original slot free for reasons I just mentioned.

What I did was:
- run a full backup
- shutdown the servers
- wait for the cache on the MSA to become flushed
- power off
- move disks
- power up
- check all logial disks

[Glenn N Wuenstel]

Gavin,
As stated this works fine. The RIS info is indeed stored on the disks and in the controller. Moving disks around as you propose not only makes sense but works.
Of course, the standard caveat of doing a backup is highly suggested if not required by internal procedures.

Glenn

[Gavin Strudley_1]

Many thanks for the responses. We have completed simultaneous moves of disks within RAID1, RAID5 and Stripesets without fault. We also moved JBODs too. We only needed to power off the MSA; the additional two shelves were left powered up without any apparent ill effect. Anything that reduces the need to fiddle with cables in the back of a rack must be good!

[Gavin Strudley_1]

Following the procedure detailed by Uwe, we have successfully migrated disks between shelves without loss of data.