EVA 8000 shelf and disk add

[NathanK]

I currently have an EVA 8000 with 8 shelves, and I am quickly running out of slots. Soon I will need to add a shelf. In the past we've always purchased 8 disks at a time (or per disk group). This takes advantage of the RSS's and mitigates any failures if a shelf goes down. Is there a way to continue this when you add more shelves?

NathanK

[Steven Clementi]

Nathan:

How many shelves are you adding?

You should continue to add disks in multiples of 8, but now that you may have a number of shelves not equal to 8, you might need to re-arrange some existing disks to get the best RSS state(s).

I would say it is probably best to add an even number of shelves like 2 or 4, rather then just 1 shelf. Adding 4 shelves would give you better flexibility when having to move stuff around.


Steven

[Peter Mattei]

If you can afford a maintenance window the easiest way is to rearrange your RSSes/drives!

Before doing the steps below take a good backup!

Steps:
1. Find out your RSS layout.
2. Mark each disk with its RSS membership.
3. Power down the EVA
4. Add the new enclosures
5. Redistribute the disk over all enclosures and in a way that only one member an RSS sits in one enclosure.
6. Power up the EVA; it will recognize the new layout and find the disks and disk groups
7. Add new drives in all enclosures

Cheers
Peter

[NathanK]

I never imagined that you could redistribute the disks. Has anyone actually done this in production? It seems like a lot for the EVA to handle.

Also, I never thought to ask before. Can you add a disk shelf without taking the array down?

NathanK

[Uwe Zessin · Accepted solution]

Yes, I have taken arrays down, added a new disk drive enclosure and redistributed the disks in order to keep a sensible RSS state. The system came up fine.

You can even power an array down, swap both controllers and after a power-up it finds it disks (I know it ;-)

While not in production I once did not want to power cycle, so I increased the disk replacement delay and moved disks while the array was running. A hell of beeps, but I didn't loose a disk.

I have also added disk enclosures while the system was up, but not on an 8000. Due to the loop switches it should be rather safe unless you confuse the loops.

[NathanK]

Very interesting!

Right now my RSS's are perfect..slot 1 of each enclosure is in one RSS and it continues all the way across to slot 13. So I imagine that I will have to first add the disks that I require, incorporate them into the disk group, and then locate the new RSS's. If they are not poperly distributed, I go through the steps that were previously described. Correct?

NathanK

[Uwe Zessin]

Correct. I guess it's hard to predict how the system responds when you add one disk drive enclosure, shuffle a few disks to it, add new disks to the array and then expand a disk group.

I have successfully done this on an EVA-3000, but I would not have been able to obtain a 'parity state' anyway.

[NathanK]

Thanks all!

NathanK