EVA: Rearrange disks when adding new enclosure?

[CA1203921]

We have an EVA 5000 that came originally with 6 enclosures, fully populated with disks. These disks are divided in into two disk groups.

Now we are going to add 2 new enclosures, but these enclosures have only 4 disks each.

I know the best practice is to distribute disks evenly across all enclosures. Whe have the opportunity to shut down the EVA, and re-arrange the existing disks to use all 8 enclosures so that we have the same amount of disks per enclosure. But is this recommended, or is it better to just leave the new enclosures with their 4 disks each, and the old enclosures fully populated?

My concern is that by moving around the disks the RSS's are going to be disarranged and perhaps causing more problems than benefits.

Any suggestions?

Thank you!

[Uwe Zessin]

You are right that one should not blindly move disks around, but it absolutely makes sense to redistribute now that you have 8 enclosures. You need to take care about the disk's RSS and their index number to make sure that paired disks do not end up in the same enclosure.

[BR788742]

Hello,

Uwe wrote that it is possible to "destroy" RSS by putting paired disks on the same shelf. My question is: Disks with which RSSID are paired? 0-1 2-3 etc... or 0-2 1-3 etc...?
Regards - Tomasz

[Uwe Zessin]

No, I don't think I wrote that. I have no idea what you mean by 'destroy'.

From what I can tell, paired disks are 0-1, 2-3, ...

[BR788742]

Uwe,
I have EVA5000 2C12D with 56 72GB disks and 96 32GB disks.All disks are distributed equally (as possible) in all shelves, I use only Raid1 Vdisks.
When I started with this configuration the RSS level was ???Mirrored???. Today, after some removing and adding physical disks and creating and deleting Vdisks RSS level is ???None"... I think that moving disks "destroyed" some RSS (paired disks are now in single shelf). I need to find such "destroyed" RSSs - maybe if I ungroup disks from them I get "Mirrored" RSS level.
Take a look at attachment - I'm little supprised with RSS 8 - it has strange RSS indexes - 0,1,2,3,6,7,8,9. I need to write some script to find RSSs with two or more disks on the same

[Uwe Zessin]

Ah, understood. I thought that 'destroy' meant loss of data.

I have a low-priority project to analyze EVA configurations and one part of this is an RSS checker, but I am missing real life test data.

Let's make a deal:
run the attached commands, put them into a .TXT file, attach to a response and I will see what I can find out.

[BR788742]

Ok, I will...

But in a meanwhile please take a look at this RSS:

72 12 0 12 7
147 12 1 10 7
146 12 2 11 7
154 12 3 5 7
134 12 4 2 9
157 12 5 2 10
52 12 6 1 5
27 12 7 6 5

(disk,RSSid,rssidx,shelf,bay). I think, that two disk 134 and 157 should be a pair and they are in the same shelf (2). I think it is wrong.

[Uwe Zessin]

I agree.

[BR788742]

I was right!
I just ungrouped two suspected disks and RSS level is now "Mirrored".
I'll send you config file after finishing migration

[BR788742]

Hi,

here is config file from my EVA after ungrouping disks and data leveling.

/T