EVA4400-Add disk enclosure

[BennyO]

Hello -

I will be adding an disk enclosure to my EVA4400 system. I know how to do this, however my question is regarding the configured disk groups. The current system has 3 enclosures, 27 disks, all in 1 disk group. Once I add the 4th enclosure with 9 more drives is there a way to have the existing disk group distribute data to the drives on the 4th drive enclosure? I would like to have the existing disk group spread across disks on all enclosures. The plan is then to create additional disk groups, and would like to have them on more than 1 enclosure. So the real question is how to I get the disk group spread onto the drives on the 4th enclosure?
Thanks for your help.
Ben

[IBaltay]

Hi,
the idea of verticality is very useful to maximize the performance as well as availability. However your config of 4 disk enclosures has the following limitation:

Limitation

the default physical subset of the disk group, called Redundant storage set by default consists of 8 physical disks. So ideal is to have minimum of 8 disk enclosures and place always the new disks in the group of 8.

Verticality

assuming that you have your disks placed across the first 9 bays of all existing enclosures, you have empty bays of 10-12.
So after the addition of the 4th disk enclosure, you can add the new 8 disks into the bays 10 and 11 across all disk enclosures. Then you can review your existing RSSes to see which disks should be physicaly reshuffled to the 4th disk enclosure after the ungroup operation, which moves all the data away from those physical disks. This should be done in a cautious way one by one always having enough free space in the disk group...

More disk groups with 48 disks which is your planned maximum is not inline with the performance best practices. The rule is the more spindles in the disk group, the more vdisk performance (the doc is for other EVAs, but the principles are the same)


http://h20195.www2.hp.com/V2/GetPDF.aspx/4AA0-2787ENW.pdf

[BennyO]

Thank you for the reply. So really the recommendation from HP is then to just add the new disks to the existing disk group that are being added with the 4th enclosure? The plan for the additional disk group was to isolate the exchange databases onto their own physical disks so that exchange I/O is on those disks only for performance reasons.

[IBaltay]

Exchange sizing tool document
http://h20195.www2.hp.com/V2/GetPDF.aspx/4AA1-1866ENW.pdf

HP Sizing Tool for Microsoft Exchange Server 2007
http://h71019.www7.hp.com/ActiveAnswers/us/en/sizers/microsoft-exchange-server.html