Suggestions for rearranging disks in an EVA 8100?

[Jeremy C]

Adding an expansion cabinet to an EVA 8100. I'd like to reallign existing disks with the new ones.

Option 1: After adding cabinet, ungroup disks one at a time and relocate. Could take a while (weeks) to get it all done.

Option 2: Rearrange the disks during the downtime of the EVA while the new cabinet is cabled up. Wil this work? Is it safe to do?

Option 3?

[IBaltay · Accepted solution]

Hi,

Note:
you need to populate all new disk enclosures with at least 1 disk.

Assuming that your current configuration of 12 disk enclosures is nicely verticaly distributed (default RSS disk count is 8). you can only continue in this direction.

The best is to create a map of existing RSSes via the SSSU.

Then either online via the ungroup/reshuffle/group operation you can involve the new disk enclosures into the DG back-end game.
(as you said it is longer method)

or you can do it offline (with a relatively short downtime) and reshuffle some physical disks (or part of the RSSes) to the new disk enclosures to have nice vertical config across the 2 disk racks (quicker method)
If you do it in the strict vertical manner, then if any of the new enclosures have problems with its backplane (multiple disk failure) it will be only a 1 disk failure in the whole DG (only 1 RSS member in each enclosure), which the DG can nicely survive assuming that such a kind of failure does not occur in more then 1 new disk enclosure at a time...

[Mark...]

Hi,
On the above point - if you are going to physically move the drives around then I would make sure I had a good backup -just in case! - as this is not supported by HP to the best of my knowledge!
Make sure that you get all your RSS info correct before you do this and you are moving the disks to make it "better" or how you what it.
DO NOT install any NEW/USED drives while you are moving your existing drives around with the EVA off. If any have quorum metadata on new/used you may find the power up interesting! Add any new/used drives once you are happy that the EVA is back up and your data is validated. Should be No problem adding in drives then.
Mark...

[Mohanasundaram_1]

Hi Jeremy,

What is your goal in planning to rearrange the disks while adding the new enclosure?
You can just add the disks in the new enclosure and get started.

Having said that, The position (slots) of disks in an EVA does not make a difference and we have re-arranged the disks of an EVA when powered-off during a lab session in an HP training. The EVA just came up well without any LUN, diskgroup, Snapshot loss.

But I am not sure if you can try such act in a production environment with so much data to protect. The best way maybe to ungroup and group one-by-one. Long haul, but sureshot way.

That is why I asked you what is your goal, at the beginning. Is this exercise worth spending days to make such rearrangement.

With regards,
Mohan.

[Jeremy C]

I think my question has pretty well been answered...and thanks for the additional warnings of gotchas.

Currently, the EVA 8100 has 12 enclosures completely full. The first 10 columns are all 300GB drives and the remaining 4 columns are all 500GB FATA drives. After adding the additional 6 cabinets, the idea is to redistributed the 300GB drives into 7 columns across 18 enclosures and the 500GB FATA drives into 3 columns across 18 enclosures. Then addd 2 columns full of 600GB drives and 2 columns full of 1TB FATA drives.

From your answers, I feel more comfortable with the slower, safer method.