MD3000i best practices

[tom11011]

Hi Group.

I was hoping to get an idea of what best practices would be for an MD3000i. Here is a little background on our purchase.

MD3000i with dual controllers, 15 - 600gb SAS 15k rpm drives

3 Dell R710 servers with the built in 4 nics, all iscsi offload capable. Each server is dual quad core, 24 gigs ram each.

We will only be attaching vsphere esx 4.0 to the san.

We will be running a general mix of windows virtual machines. One of these virtual machines will be sql 2008 which is expected to be light to medium duty. Two of the virtual servers will be citrix xen app servers. The rest will be your garden variety domain controllers, web servers, share point, print servers.

Basically, I think I know what I want to do but am looking for validation or tips I might not have thougth about. I've never used the MD3000i before and for that matter, iscsi. We have always been EMC fiber channel.

So I was thinking that one drive would be a hot spare leaving 14 left. This is where I need a little advice.

Does it make sense to stripe the remaining disks as raid 10 for best overall performance? Should it be 1 raid group or should I think about maybe 2 raid groups (6 disk and 8 disk)? Raid 10 will leave us with 4.2tb usable space and that is more than sufficient for our needs.

Then the next question is does the lun size matter? I see no valid reason to carve up more luns than are really needed. On our EMC clarions, we have luns all over the place but it is useful as we migrate them and resize them all the time. This was before thin provisioning and we also have non vmware servers attached to the EMC for general sql clustering.

The only other thing that I think would be nice is to have a piece of the storage dedicated to backups. We are investigating vizioncore for vm backups and I might like to store backups here as well.

Any advice or tips appreciated!!

thanks in advance.

[golddiggie]

I would create a single array out of all the drives available. Use the RAID level that makes the most sense for your needs. If that's RAID 10 (most likely giving the best performance, with high redundancy) then by all means, use all the drives in that configuration. RAID 50 or 60 would be alternative choices, but RAID 10 is still probably the best bet. I would not split the MD3000i into two arrays since you'll actually have lesser performance due to less spindles in each array.

For LUN size, I would make them all in the 500GB to 1TB size. You can go up to 2TB-512B if you really need something that large. You shouldn't have any performance hit by using more LUNs on the array. It will make management easier if you can settle on a standard LUN size.

Are you planning on using thin, or thick, provisioning for the VM's?

VCP4

[tom11011]

Thank you for your response. I'm thinking thin provisioning as an option because it is available and very flexible.

[golddiggie]

Then just be sure to have the overallocation alarm set so that you don't over-provision the storage.

VCP4

[AndreTheGiant]

For LUN sizing see:

For the number of Virtual Disk on the storage I suggest to keep at least 2 different RAID group with different disk sets.

This because I suppose that you have 2 controllers, and on MD3000i each VD can be "active" only on one controller.

So with at least 2 different VD you can improve performance, by simpe set different controllers as prefered owner.

For more info on MD3000i see also:

http://www.delltechcenter.com/page/VMwareESX4.0andPowerVault+MD3000i

Andre

[tom11011]

Thank you.