ESXi disk setup for SQL server VMs - advice sought

[fox1977]

Hi folks,

 

Just after a bit of advice about the RAID hard drive setup on a new physical host we are putting in to run a couple of virtual SQL servers. I am looking at putting in a Dell 2950 with 16gb RAM (with space for another 16gb taking it to 32gb) and a lot of direct attached storage. My question is really around the RAID config. I am looking at running possibly 3 machines at needing about 300-500gb each storage each.

 

I know for physical servers we try to setup the system, transaction logs and data files on separate disks. Some of our servers were split between two raid controllers and a number of physical disks. Do we still need to plan the virtual machines along the same lines. I was thinking that we do not need to set them up in the same manner as the underlying physical setup is different. I am thinking about putting the system os on a 20gb partition and a massic 300gb data partition.

 

At the moment we do not have a budget for shared storage but I am hoping we can get something sorted in the next few months.

 

I am thinking about whether to go with RAID 5 (5 or 6 x 1tb SAS or SATA drive) or RAID 1+0 with a number of 1TB drives. What setup is going to give me the best performance? I have heard stuff about the more spindles the better. I'm assuming spindles means drives!

 

We are going to be converting/migrating 2 machines that are running on dual AMD 2218 2.6ghz with 4gb RAM on direct storage. Just run a few sql counters over one of the boxes and it is averaging between 60-100 transactions per second the other box is averaging about 350 per sec. We are also looking at upgrading SQL from 2000 to 2005.

 

Any tips and ideas gratefully received

[Theblacksheep]

If you're after performance, 5-6 raid5 15k SAS would be the way to go and is recommended with ESXi for SQL drives.

[Butuz]

Be careful with using DAS on ESXi.

 

Why? Because ESXi is not very good at moving VM's around between storage devices. If your using DAS and your raid card failed, or motherboard, you could be looking at lengthy downtime while the server is repaired.

 

If you use iSCSI SAN you will not be reliant on your server hardware, i.e if your server fails, you could simply unplug it from the SAN and then plug another totally different server in and get it up and running fairly quickly with little down time.

 

Butuz