Adding more disks to existing disk groups

[Ebk]

Hi

I need to add more disks into our existing disk groups.
I have attached the current setup and would like to know the recommandations to integrate the new disks.

I want to add 8 disks into the disk group 1 and 16 in the disk group 2.

Finally I would like to know what is the size limit for disk group?

Many thanks

[IBaltay]

Hi,
a) the best practice is to add the new disks in the group of 8 to create the default new RSSes.
b) for the disk group sizing see the eva perf best practices:
ftp://ftp.compaq.com/pub/products/storageworks/whitepapers/5982-9140EN.pdf

one rack config is up to 168 disks
two rack config is up to 240 disks
so the best is to have as less DGs as possible:
e.g. 2x84 and 2x120 or 3x80, from the disk distribution point of view, the back end performance grows almost linearly till the count of 80 disks, ...
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00365744&cc=us&dlc=en&lc=en&jumpid=reg_R1002_USEN

[Víctor Cespón]

You currently have 12 disk enclosures, so it must be an EVA8000 or 8100. All the disks on each disk group are the same size.
A disk group can contain up to 240 disks (adding an expansion cabinet to the EVA with 6 more enclosures).
Add disks following column order, so they are distributed among all the enclosures.
so in this case you'll add 8 disks from column 5 to one group and the rest to the other.

[Ebk]

thanks for the reply.
Just one more question: Is there any advantage to start from bottom or the top?
I have reattched the planned work after reading the pdf and your recommandations.

Thanks again!

[IBaltay]

that is ok, and to stay fully vertical in the RSS group
a) 8 in bay 5,
b) 4 bay in 5 and first 4 in bay 6
c) 8 in bay 6

Note
before the group add the disk physicaly into bays in the groups max of 4 disks and wait approximately 1 minute for the initialization of all added disks...

[IBaltay]

so there is no difference between the addition them from the bottom to the top but there is a difference to let them nicely vertical (across 8 physical enclosures) not to have them 2 in one enclosure...

[Ebk]

I realize that your option C) sounds like the one I need to go for to leave the disks of disk groups 2 all together. at least for now...

Thanks

[Ebk]

Thread closed.

[IBaltay]

nono, it is my mistake, i wanted to say no matter where you will plug the new disks that it is always good to have it in 8 - verticaly across 8 physical bays...

[IBaltay]

errata not bays but enclosures... :-)