DS3300 Design - RAID and logical drive configuration

[iancampbell]

Hi,

I'm configuring a dual controller DS3300 with 2 x VMWare ESX 3.5 hosts connecting using the software iSCSI initiator. I have a question about optimal drive configuration. From what I've read I should configure multiple logical drives and then assign each logical drive a different preferred controller owner. I have 12 300Gb disks so I was thinking that I would create an 11 disk RAID5 array with 1 hot spare. I would create 4 x logical drives of equal size and will then assign each of the 4 controllers so that traffic is spread out across the controllers for optimum performance.

A1 and B2 go to a different physical switch (vlan) and B1, A2 go to another. Each ESX server has 2 vswitches each with a single network adapter with each going to a different physical switch.

Can anyone advise if the above RAID and logical drive design is the best way to go for optimal iSCSI throughput? I am not asking about what type of raid to use - I don't need a raid 1/0 or a mixture of performance - I am only concerned about getting the best iSCSI performance for RAID5. Should I create multiple RAID5 arrays and logical drives or just multiple logical drives?

Thanks,

Ian

[azn2kew]

I suggest you read Chad Sakac's iSCSI design more details Chad Sakac's post on the topic .

If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!

Regards,

Stefan Nguyen

VMware vExpert 2009

iGeek Systems Inc.

VMware, Citrix, Microsoft Consultant

[christianZ · Accepted solution]

If you have 2 controllers in your storage then the best config (with 12 disks) should be to configure 2 R5 arrays - each of them has its owning controller.

The included logical drives will have the same owning controller as the parent array. The logical drives could be ca. 300-500 GB on size. Making one big R5 is not the best practice because of likehood of double disk failure (e.g. during the rebuild time). One spare is a must here.

On Esx site I would keep all simple - 2 nics, one vmkernel iscsi port. More complexity won't get you more throughput (with that storage).

Just to notice - the DS3000 series give quite more random ios on R10 in comparison to R5.

[iancampbell]

Thanks guys. Very helpful.

[JohnADCO]

It does somewhat come down to how your san model does it's controller to disk ownerships....

Some sans do it by Virtual disk and not disk group, so you can divide up ownership even on the same disk group. Quite a few different schemes bewteen models on this actually.