P4000 SAN to support 2 physical servers and 6 VM's?

[Laurence Chiu]

I am looking to replace 5 real servers (usual suspects, Exchange, File/Print, SQL, OWA, ISA) with 2 virtual servers running 5-6 VM's using Windows Server 2008 Hyper-V. This is to support a fairly stable workload for 60-70 people.

We have a storage issue now with the DAS (about 600GB) and think a SAN is a better way forward.

Looking at the HP offerings it seems that the LeftHand P4000 SAN solution would suit us. We would need to be able to store our VM images on the SAN, boot from it (or is it boot from USB device now and then load the image from the SAN) and store all mail, SQL database etc. on the device. I think the 4.8TB configuration would do us for a while.

I guess I had two questions.

1. Can this device support Hyper-V and booting from it?

2. I read somewhere that Hyper-V cannot allow VM's to share LUNs but I am not sure in our environment that is an issue. Should I be concerned about that? I don't see a regular need to create/destroy VM's in this environment.

Thanks

Larry

P.S. This thread ahs been moved from Storage Area Networks (SAN) (Enterprise) to HP StoreVirtual Storage / LeftHand - Hp Forum Moderator

[Prokopets]

1 Yes.
1.1 Well... I supports boot-from-san, it supports Hyper-v, so why shouldn't it support boot hyper-v from san? :) Or, i think i misunderstood your question...

2 Afaik, the main idea of a lun sharing is a clustering. So, if you won't use clusters into Hyper-V (it supports failover cluster without lun sharing, afaik) - you don't need it.

[Laurence Chiu]

Thanks - just what I wanted to know. If I can boot from the P4000 then I think that solves my problems

[Prokopets]

Can you clarify - do you want to boot host os from san? If yes, what's the point of doing so?

[Laurence Chiu]

I guess I want to have the VM environment so that storage is virtualised also so the various VM's don't need DAS to boot up.

Does that make sense?

[Prokopets]

Laurence, that's ok, if you're going to place VM's on the storage, but i'm not sure if it's ok to put on the storage the host os.
Well, anyway, if it will be slow (i mean disk i/o)- just add a couple of disks to the server - just for host os, and that's all.

And one more thing: in all cases, don't forget about good NIC (with normal TOE and hardware iSCSI accelerator).

[Steven Clementi]

Typically, the way a Virtual environment is set up is as follows...

You have a server that runs your Virtualization platform... Windows HV, VMware ESX, XEN, etc... This is the "Operating System" for the physical server. Usually this is installed on local hard drives and does not require a lot of space. A Pair of 72GB HDD's is usually sufficient.

Now, you have external storage. The storage gets presented to the server somehow... Fibre.. iscsi... whatever it may be. This becomes yor "datastore" (there might be different terms for different platforms.. I am using the VMware terms).

Your datastore is where all of your Virtual Machines reside. In this case, on a P4000. So in fact... ALL of your VM's are "Booting from SAN" while your Physical server is booting from local disk.


Steven

[Laurence Chiu]

That all sounds good. As noted a local HD to boot the host OS from isn't going to be a big issue. In fact I have heard now that the servers can boot the host OS from USB.

But one question was asked that I wasn't so sure about. What about physical swap space? I am guessing the host OS and virtual hosts need swap space and even if they are given enough real memory, swapping is inevitable. Not sure what swap performance would be like over iSCSI as the P4000 or should the swap files also be locally atttached storage on each of the real host machines? And then can the VM's also be told to use that space rather than virtual store which might be on the P4000 and therefore across the network?

[Prokopets]

Laurence, generally, if you'll give enough memory to guest osee - they won't use swap very actively.
And yes, i've heard some recommendations from Ms about putting swap on the DAS in case of booting from SAN (it was quite a long time ago and i can forget some moments..).
So, you can get some "insurance" from this issue by buying a raid-controller for the server with BBWC and in case of a problem with the swap load - you can just move it on the DAS.