What hard drive types, and RAID level, for Virtualisation

Over Clocker · 24 Jul 2010 at 15:57

Hi guys,

AM going to be moving our Hyper V virtual machines onto a new array in the next few weeks (it is currently on the same array as the host).

We have a spare Adaptec 5405 SAS / SATA controller that we will use.

I am just wondering what RAID array would offer the best reliability / speed configuration? Would be looking at getting 4 hard drives. We'd need around 1.5TB of space after RAID.

Thanks,

Mal

ecksmen · 24 Jul 2010 at 16:22

Over Clocker said:
Hi guys,

AM going to be moving our Hyper V virtual machines onto a new array in the next few weeks (it is currently on the same array as the host).

We have a spare Adaptec 5405 SAS / SATA controller that we will use.

I am just wondering what RAID array would offer the best reliability / speed configuration? Would be looking at getting 4 hard drives. We'd need around 1.5TB of space after RAID.

Thanks,

Mal

It largely depends on the machines and what they do, though it sounds like RAID5 will be your only option for your size and disk count unless you go sata.

SMN · 24 Jul 2010 at 16:46

One more vote for RAID 5. Depending on the ports available, probably a 4+1 configuration as standard would be my suggestion.

Over Clocker · 24 Jul 2010 at 17:04

Cheers guys. Will be running 4 VM:

DC1
DC2
Exchange 2007 / BES (6 mailboxes)
File server (500GB)

Also a WinXP test VM and Win7 test VM

Thanks

PistolPete · 24 Jul 2010 at 17:05

RAID5 is going to suck on the disk writes, even on a hardware controller.
It gets worse the more VHDs you are using, and how much activity they'll see.

RAID10 would be better but that would mean 4x 750Gb drives minimum, ideally 4x 1TB to give you 1.8TB space.

PieMaster · 24 Jul 2010 at 19:16

We used to have RAID5 on one of our UAT HyperV machines (for the same reason as you - to maximise capacity) and it got very painful very quickly. All of them are now configured with a RAID1 for the host OS and a 4x 1Tb 10k SAS disks in RAID10 and we have very few performance issues with them which is impressive considering our applications are latency bound by synchronous log file writes.

Major_Disaster · 24 Jul 2010 at 20:02

PistolPete said:
RAID5 is going to suck on the disk writes, even on a hardware controller.
It gets worse the more VHDs you are using, and how much activity they'll see.

RAID10 would be better but that would mean 4x 750Gb drives minimum, ideally 4x 1TB to give you 1.8TB space.

/agree

ecksmen · 24 Jul 2010 at 21:01

PistolPete said:
RAID5 is going to suck on the disk writes, even on a hardware controller.
It gets worse the more VHDs you are using, and how much activity they'll see.

RAID10 would be better but that would mean 4x 750Gb drives minimum, ideally 4x 1TB to give you 1.8TB space.

While I don't dispute the performance, what drives worth having offer this capcity? If the only constraint was 1.5TB but he has said they've only got room for 4 drives (I assume perhaps incorrectly this is a physical constraint).

I don't think this is an debate as to which raid offers best performance.

s0ck · 24 Jul 2010 at 23:07

you may find you'll be moving the array again if you go raid5

Stelly · 26 Jul 2010 at 08:11

Over Clocker said:
Cheers guys. Will be running 4 VM:

DC1
DC2
Exchange 2007 / BES (6 mailboxes)
File server (500GB)

Also a WinXP test VM and Win7 test VM

Thanks

I know that this is none of my business but both your DCs on one Hyper-V server, is that a good idea??

Also how do you find BES virtualised? I heard it runs like a right dog!

Stelly

Dunks · 26 Jul 2010 at 13:35

Also, isn't it better practice to run DC's on hardware level rather than virtualised?

iaind · 26 Jul 2010 at 16:28

Dunks said:
Also, isn't it better practice to run DC's on hardware level rather than virtualised?

Nope

I'd agree that I wouldnt want both (if there are only 2) on the one physical box, but nothing wrong with running them virtual

MasterPlan1 · 27 Jul 2010 at 11:51

Stelly said:
I know that this is none of my business but both your DCs on one Hyper-V server, is that a good idea??

Also how do you find BES virtualised? I heard it runs like a right dog!

Stelly

In my old corp, and current corp, BES is virtualised, and runs alright, currently we don't have that many here as we're trying to ditch BB's and move to droids. But previous we had like 1000 users on our BES5 box which was running on ESX 3.5.

Stelly · 27 Jul 2010 at 13:10

Dunks said:
Also, isn't it better practice to run DC's on hardware level rather than virtualised?

MS best practice says not too last time I looked...

Stelly

kippermitten · 2 Aug 2010 at 15:16

Mt two pennies.
In this scenario of;
DC1
DC2
Exchange 2007 / BES (6 mailboxes)
File server (500GB)

You really must go with RAID 10 and at least 4 disks, ideally IMO 8 for a 4+4 array.
The DC's and Exchange even with 6 people need decent write I/O which will end up being a bottle neck with RAID 5 as the write penalty is very high.