Brand New Setup with VMWare

[prutter]

Hi All,

Sorry if this has been asked a thousand times but here goes. I am new the virtual world adn about to dive in head first. I seem to have a lot of issues with what type of disks to use and whether to use iSCSI or FC. We are a relatively small shop, about 100 users adn we have about 14 servers that can all be virtualized...i think. The only things that I believe we have that might be disk write intensive is a small SQL box adn my exchange server. I am planning on making them VM's unless i hear a lot of arguments to the contrary. That being said, i would like some opinions or facts to help me out on the SAN issue (if it's preferred over NAS in a VMWare environment) and if the disk can be SATA drives. I hear some talk about not using SATA drives because they are not fast enough but i read stuff that doesn't support that. Due to the size of our shop and the current disk space we have accumulated over the years (1 TB) it looks like all we need is an ENTRY level SAN and there are some supposed drawbacks to that. The other alternative is a HIGHER prices SAN which is going to be a bit harder to sell to the "big Guy". If anyone had anything they can share on this subject i surely would appreciate it. Any other tidbits of info are welcome as well. thanks in advance.

Perry

[Aldebaran]

Perry,

I'm not familiar enough with your particular situation, but here is some guidelines and question I think are important.

1) Select the correct virtualization product. Have you looked at VMware ESX Server, which is an operating system that supports virtualization vs. VMware Server, which requires a host operating system to support virtualization? Based on some of your requirements (high performance, 14 virtual servers, many users), ESX Server might be the better way to go. If you go with ESX Server, you'll have less choices for hardware; but it will be easier to manage and configure that multiple Windows or Unix boxes running VMware Server.

2) I would go with an iSCSI SAN over FC, especially if cost is an issue.

3) SAN vs. NAS. Regardless of whether you chose ESX Server or Server, I think that SAN generally has less overhead when doing I/O.

4) If you are thinking about ESX Server, call VMware pre-sales technical support and have them specify a configuration for you.

Whatever hardware you get for doing virtualization, load it up with memory. I can't stress this point enough.

Jeff

[prutter]

Hi Jeff,

I am certainly going with ESX server and i just need some input on the best type of infrastructure to go with it. I would hate to find out 6 months down the road that an iSCSI SAN was not the way to go. Those are the things that i am trying to avoid. Thanks for the response.

Perry

[Ken_Cline]

Perry,

The "best of breed" solution is going to be a FC SAN - but that's also the most expensive option. Based on what I'm hearing you say, you're definitely in the "entry level" arena, which means something like an HP MSA or an EMC AX. Either would probably meet your needs for the foreseeable future.

If you want to "future proof" your environment, then step up a level and look at the low end of the HP EVA, EMC CX, or something from IBM.

That's the FC options - next, I would look to an iSCSI solution. There are lots of them out there, and most are going to be less expensive than their fibre brethren (especially if you're starting with a clean slate). You'll probably get "good enough" performance out of an iSCSI solution unless you're running some heavy I/O systems (which it doesn't sound like you are).

There are lots of folks here that are using NAS filers (NFS) - I would not recommend going that route. Performance is not the issue, it's simply that you don't expose block level access to your storage. That means that you can't take advantage of any current or future VMware features that require block level access (VMFS, VCB, etc.). While you may not see anything that's compelling in the current feature set - what happens when ESX 3.5 (or whatever) comes out with something really cool that requires block level access and you're using NFS?

So...to sum it up:

If you can afford it, go with a FC SAN. It will provide the best performance you can get (today).

Second choice (and still a good one), is an iSCSI SAN. It will provide good performance and feature protection.

Third choice is a NAS filer. It will provide good performance but could leave you out in the cold for future feature use.

Last choice is local SCSI disk...gives good performance but locks you out of multi-system feature sets (VMotion, DRS, HA, etc.)

KLC

[prutter]

Hi Ken,

thanks for the great reply. that makes things a lot clearer. One other question that i had was concerning the drives. How much am i going to suffer if I go with a SAN that is running SATA drives at 10K RPM. I'm hearing a lot of mixed signals about this. I think we are definately in the "entry level" arena as far as a SAN goes but the draw back, i think, is the type of drives. Any thoughts? Thanks again for the reply

Perry

[Ken_Cline]

How much am i going to suffer if I go with a SAN that is running SATA drives at 10K RPM

Well...again, that's going to depend. It's not going to be "as fast" as FC or SCSI...but what's really going to make the difference is the controller & cache therein...

[prutter]

Ken,

Thanks for all the info!! I appreciate it.