reorganize redundant storage sets (RSS) EVA8000

[SJO EGGER]

hello

we have 2 EVA8000 2C8D and would like to add 2 more shelfes in each storage. now we have the RSS over 8 shelfes with allways 8 disks (i think the best solution you can have). will the EVA system reorganize the RSS after adding 2 shelfes and make RSS of 10 disks or did we get new RSS on these two shelfes?

thanks for your answer.

[IBaltay]

Hi,
the RSS algorithm is not doing the automatic logical reshuffle after the new enclosure addition, so it has to be done manually.
It can be done
a)offline (quick, but downtime needed) - in this case you need the map of the original RSS members physical location to see which disks need to should reshuffled after the EVA shutdown

b) online (slow, without the downtime)- (based on the map of the original RSS member physical location)
after the 2 new enclosures addition, the new RSSs will be placed in them only. You can online do a manual logical reshuffle via the pair ungroup/group operation. ( Note -The RSS members need not be in one bay verticaly, but they have to be vertical across all bays)

[Steven Clementi]

The answer is no. The EVA will NOT reorganize RSS's to have 10 members instead of 8. You will always have RSS's of 8 disks. Any new rss's will/should include disks that are on the 2 new shelves.

I was told there is a way to make the controllers set up RSS's in groups of 6 disks, but this was only on the EVA8x00 and I have never seen it/done it before. Also, you would only do this if you had shelves in multiples of 6 (12 or 18 shelves total).

The way RSS's work and the way the controllers build them...

You start with a disk group of 8 disks. The controllers make 1 rss.

You add 1 disk, your rss is now 9 disks.

You add 1 more disk, your rss is now 10 disks.

You add yet another disk, your rss is now 11 disks.

When you add the 12th disk, the controllers split the rss into 2 groups of 6 so now you have 2 rss's.

Adding 4 more disks at this point, the controllers will put 2 in rss1 and 2 in rss2 to make them 8 disk rss's.

If you were to add 5 disks at this point (instead of the 4)... 17 total disks, the controllers would add 2 to rss1 to make an 8 disk rss, then add 3 disks to rss2 for an 11 disk rss.

The process continues in the same manner as you add more disks.


This is one reason why the best practice is to add disks in multiples of 8, so that the controllers don't do the rss shuffle.


Steven

[IBaltay]

maybe this thread could help you to see how it can be online redesigned to fully vertical
http://forums12.itrc.hp.com/service/forums/questionanswer.do?threadId=1268947

[D. v d Coevering]

The answer was already givin, no no auto reorganization of RS sets and yes your new RS set will be in those newly added diskenc. only.

From opinion it would have been better to buy an additional 4 (12 total) diskenc. for the simple reason that you've the filled the entire cabinet.

From own experience I can tell you that reorganizing the RS sets is fairly simple.
First you have to find out how this can be done in the least amount of steps (swapping the disk to new location).
Then you should increase your disk replacement timer to give you and the disk ample time to spin down and rejoin the array (I used 10 minutes). If the timer should expire a rebuild en leveling will start.
Swap the disk according to plan one at a time and check CVE that it comes back.
If not try to reseat the drive. When the drive is back continue with next disk.

[D. v d Coevering]

IBaltay , what's the purpose off swapping disk after ungrouping?

To my knowledge when you should ungroup a drive there's no RS information on it, check drive information after an ungroup.

I've been doing RS reshuffles using ungroup/ group action without swapping drives and that works fine.

And in me previous reply the drives where swapped while grouped to a better location (RS whise).

Grtz Dion

[IBaltay]

Hi,
In my previous post I have named the ungroup/regroup as Logical reshuffling :-) to be absolutely clear what happens from the RSS point of view. No physical reshuffling is needed here certainly...

[IBaltay]

Dion,
there is no need to add 4 enclosures in this case (when there are allready 8 which which is RSS default number of physical disks). From 8-10, the only problem is to keep the RSS algorithm from creating RSSs with 11 members, because "we have only 8-10 enclosures" and thus we will not be fully vertical. Thats why the best is keeping the Best practices and add the disks in 8 to create always the new default RSS with no regards of the verticality in the first step (2 new enclosures means 2x14 disks at max and SJO EGGER is free to add 8, 16, 24 physical disks - with the grouping of 8 at a time.
Then he would have the new RSSs spread horizontaly across the new enclosures.
Then he can do a map of the RSS locations and the ungroup/regroup procedure to establish the full verticality can start...

[D. v d Coevering]

IBaltay, Thanks for your answer, I guess i misread your post and your right thats there is no need to buy 4 enclosures. But I never said that, I only said that in my opinion it would have been better.

My reason being that topicstarter will most likely will expand his EVA's in the (near) future and had to do another RS set reshuffle.

[SJO EGGER]

thanks vor those greate response in this thread!

just to be sure that wie mean the same with ungroup/group (look at the attached excel):
1.) i ungroup one disk in rss1 and group the disk d1 and this disk will be added in rss1?
2.) then i group the disk which i have ungroup before and this one will also go back into rss1?
3.) i ungroup again one disk in rss1 which have now 9 members and add disk d15 which will
become a member of rss1 and group the other disk again?
4.) now i have in my rss1 10 members?

you see all the question marks because i cannot beleve this procedure.

please help me again. i would like to have 14 rss with 10 disk over all shelfes vertical.

thank you.
roland