A hard drive each or use a stripe?

I want to run VM images on a new computer that Im going to build. Should I run 2 VMs off one hard disk each (OS on a different disk) or run 2 VMs off a 2 disk stripe (again OS on a different disk). Which would offer better performance?

Or would a cheap NAS offer better performance?

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RTmarc

What are you going to be using them for? Testing or production? Just curious because you don't really need a large disk for most VMs. Personally speaking, the vast majority of my VMs never exceed 20-25GB in size.

Striping is definitely going to yield more performance but you do have a pretty hefty point of failure. Should one of your drives die, you'll have lost everything striped across the drives unless you back it up regularly or use a RAID 5 config.

JDMurray

Most of the VM performance problems occur when writing to disk. Therefore, file system fragmentation, slower disk drives and controller technologies, and RAID configurations that degrade write performance will be your primary enemies.

hetty

Just labs & testing out stuff, so Im not worried about redundancy. I can copy the images back over from my other hard drive again if a stripe went kaput. I will be running more than 2 VMs off this new setup but if I run a few together at the moment it all gets a bit too slow and frustrating. Running a dual-core with 2gb of RAM.

Im going to go to quad-core & 4Gb on the new setup but like you say JD, I think its mostly the hard drive which is causing everything to slow down. So for the new setup, I need to separate them, stripe them or NAS them cheaply; but I dont know which would offer the best disk performance if Ive got a few VMs running at the same time.

JDMurray

What VM software are you using? Check if it can properly use a multi-core CPU, otherwise you'll find better performance running the VM's on different computers. And make sure you are using SATA drives and controller, where each disk has its own I/O channel.

Sie

I will be running more than 2 VMs off this new setup but if I run a few together at the moment it all gets a bit too slow and frustrating. Running a dual-core with 2gb of RAM.

Im a bit concerned over this to be honest, What OS's are you running together to get the slow performance?

Have you setup the RAM requirements of each machine correctly?

I have run 2 servers and 2 clients off my Dual-Core & 2GB setup fine, this is even in Vista with its large RAM overheads for the Host OS anyway.....

I think you may be able to save money by configuring your VM settings better rather than putting more RAM in.

Also I have had no problems with Readyboost and Virtual PC/Server as of yet that may be another option for you?

hetty

I sometimes have 4 Server2k3 or 2 Server2k3 and a client. I should explain I have a small Dell which only has 2 SATA ports, one for the hard drive, one for the DVD-RW. And because its a small case, a normal SATA controller card wont fit in to the slot properly (about a quarter of it sits above the clip to hold it down) and I don't have any proper internal space for an extra hard drive even if there was an extra SATA port. Bad call on my part, I thought that all cases worked with all normal sized PCI cards. Going to sell my old computer to a friend and custom build my new setup. I should have at least 6 SATA ports this time and I can setup RAID.

Using Workstation 6 on XP, setting images to dual-core, giving each Server2k3 384mb if I have 4 or 512mb if im only using 2, start one, let it load, start the second, and so on. Giving XP client 128mb. I was thinking of running two separate computers but then decided against cause if I got a quad-core it would be a good gaming machine also.

I couldnt find anything on google, so I might just setup the two disks and run some type of performance monitor, then setup the stripe and run it again and see which gives better IO. I thought there might be some solid info on the web but I cant seem to find any.

JDMurray

hetty wrote:

I should explain I have a small Dell which only has 2 SATA ports, one for the hard drive, one for the DVD-RW. And because its a small case, a normal SATA controller card wont fit in to the slot properly ... and I don't have any proper internal space for an extra hard drive even if there was an extra SATA port.

Put a hard drive on each SATA channel and use an external USB DVD-RW. You can put the second hard drive where your DVD drive is now.

hetty wrote:

Using Workstation 6 on XP, setting images to dual-core, giving each Server2k3 384mb if I have 4 or 512mb if im only using 2, start one, let it load, start the second, and so on. Giving XP client 128mb.

128MB of RAM? Windows 98 will hardly run well with 128MB of RAM. And I realize that the minimum RAM requirements for Server 2K3 is 128MB, but be prepared for very sluggish performance with a lot of swapping to the page file.

hetty wrote:

I was thinking of running two separate computers but then decided against cause if I got a quad-core it would be a good gaming machine also.

Very few games can properly use a multi-core CPU. For gaming you are better off with a higher-end graphics card than a quad core CPU.

hetty

Im going to get a NVidia 8800GT so I think it should be OK for most games. But I cant put that in to my current PC because of the case & power supply. I think its time to replace it with something thats more suitable for running more labs and better gaming.