MD3000i Disk Groups and Lun Sizing

[manfriday]

Hi,

As I mentioned in another topic, I was instructed by Dell that it would be a good idea for me to blow away the LUNS on my MD3000i and start over from scratch.

According to Dell's best practice, no more than 4 virtual disks (luns) should be created for any one disk group (raid set).

My MD3000i is filed with 1 TB SATA disks. Unless I am understanding things incorrectly, limiting myself to no more than 4 LUNS per raid set is going to result in LUNS larger than what I think would work best with VMWare.

I wanted to try to keep most of the LUNS between 300-500 GB, limiting them to no more than 8 VM's per lun.

I guess what I am asking is what other folks ahve done with their MD3000i's as far as creating thier disk groups and slicing up their luns.

What about segment & strip size?

Thanks for any input you can offer.

[AndreTheGiant]

With this kind of storage I prefer to have only a single LUN for each RAID group, just to have LUN I/O that goes on different disk.

But in your case is not simple, cause you have very big disks and with ESX there is the limit of 2 TB - 512 B for each LUN.

Cause you are using SATA disks I suggest to create at least a RAID1+0 group.

I wanted to try to keep most of the LUNS between 300-500 GB, limiting them to no more than 8 VM's per lun.

You must count how many VM are on the same RAID group cause write operations could be a problem (with a lot of LUNs and a lot of VMs, maybe on a very big RAID5).

What about segment & strip size?

See for example the best practice for Exchange:

http://www.dell.com/downloads/global/products/pvaul/en/exchange2007-md3000-i-bestpractice.pdf

Remember to follow the MD3000i network topology to have 4 paths and use Jumbo Frame (supported on vSphere).

See also: http://www.dell.com/downloads/global/solutions/md3000i_esx_deploy_guide.pdf

Andre