Hardware guide - many concurrent virtual machines

[Thomi]

Hi,

I would have thought that this was a popular questions, but searching the forums & documentation hasn't revealed anything. If anyone can point me in the right direction that'd be great.

I need to test some software on a large (30-50) number of PCs in a networked environment. Obviously, acquiring this number of physical machines just for testing will be too expensive. I'd like to use virtualbox to virtualise these hosts. I'm reasonably sure that virtualbox will do everything I need. I'm planning on buying a new machine - it's sole purpose will be to run virtualbox. What I'm looking for are some tips for purchasing the hardware for this new PC.

First, the details:

I need to run a minimum of 30 virtual machines concurrently. They won't be doing much (the software itself is very light). The guest OSes on these machines will be a mixture of windows XP, windows vista, windows 7, and various Linux distributions. The VMs will most of the time be idle - although occasionally there will be some user interaction.

I'm looking for some information like:

* I assume that a multi-core processor will bring benefits to this kind of setup - will a single quad-core CPU suffice, or do I need to get into the realm of SMP setups?

* Regarding disk access, is it worth building a fast RAID-5 array, or is this overkill? As I mentioned, there won't be a lot of disk access by the software I'm testing, but I guess guest OSes still doa fair amount with the disk.

* RAM - how much do I need? I guess we're talking about 16GB minimum, which gives ~500MB per guest. Some guests can run with less, some with more (WinXP, and some linux OSes seem to run fine with 256MB or even less, whereas vista & windows 7 seem to need a lot more).

* Host OS - are there noticble benefits of one host OS over another? I was planning on running Linux without an X setup and connecting to the VMs via vRDP . RDP / VNC. Is this a good idea?


I am surprised that there doesn't seem to be a page in the user manual that contain rough "rules of thumb" regarding the physical hardware required to run a single VM. I'm hoping someone here has experience with a similar setup and can provide a few hints / tips.

Cheers,

[sandervl]

A similar topic can be found here.

[Thomi]

A similar topic can be found here.

Thanks - I'm sorry I didn't see that earlier. It only answers some of my questions though I'd still like to see some information regarding optimising host hardware & software for virtualisation. For example - regarding disk access, I assume low latency access is more important than high throughput? It'd be nice to have a page somewhere that says something like:

To optimise a host machine for running multiple concurrent virtual machines, you should consider the following: X Y Z

Obviously optimising is best done to the specific scenario, but some general guidelines would be useful.

Any thoughts?

[sandervl]

The problem really is that it's hard to make suggestions as it all depends on the use case. Keep in mind that e.g. during booting XP reads +- 150 MB. Vista and 7 probably quite a bit more.
Throughput is important as is latency. Also depends on how aggressive the host OS is wrt disk caching.

With dozens of VMs you do want a fast disk subsystem. Otherwise startup will take quite some time. For a test scenario with mostly idling guest you wouldn't really need a very expensive solution, but keep in mind that e.g. Vista is quite terrible when it comes to preloading files.

[NeBlackCat]

Isn't this type of thing what ESX was designed for, and vbox wasn't?

[sandervl]

Isn't this type of thing what ESX was designed for, and vbox wasn't?

Of course VirtualBox can handle such situations. Many customers of ours are using it in that way.

[Thomi]

Isn't this type of thing what ESX was designed for, and vbox wasn't?

You may be right - I don't know. However, I find that virtualbox gives me a much greater flexibility - since this is a test environment, I'll be adding, removing, and generally messing around with the VMs often. The way I see it, ESX is probably more suited to a more stable, production environemnt, although I'm sure virtualbox can be used there as well

[NeBlackCat]

Isn't this type of thing what ESX was designed for, and vbox wasn't?

Of course VirtualBox can handle such situations. Many customers of ours are using it in that way.

I thought vbox was the desktop product within Sun's virtualization portfolio, sorry if I was wrong.

[sandervl]

I thought vbox was the desktop product within Sun's virtualization portfolio, sorry if I was wrong.

No problem. VirtualBox is used in Sun's VDI (Virtual Desktop Solution) too. Just keep in mind that one use doesn't exclude the other.