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I am managing a few cheap servers as my user base isn't large enough to get much more powerful servers. I also don't have the money lying around to invest in a server to prepare for the larger user base. So I'm stuck with the old hardware I have.

I am toying with the idea of virtualizing all the current OS's with most likely VMware vSphere Hypervisor (AKA ESXi) Xen (ESXi has too strict of an HCL, and my hardware is too old). Big reasons for doing so:

  • Ability to upgrade and scale hardware rapidly - This is most likely what I'll be doing as I distribute services, get a bigger server, centralize (electricity bills are horrible), distribute, get a bigger server, etc... Manually doing this by reinstalling the entire OS would be a big pain
  • Safety from me - I've made many rookie mistakes, like doing lots of risky work on a vital production server. With a VM I can just backup the state, work on my machine, test, and revert if necessary. No worries, and no OS reinstallation
  • Safety from other factors - As I scale servers might go down, and a backup VM can instantly be started.
  • Various other reasons.

However the limiting factor here is hardware. And I mean very depressing hardware. The current server's run off of a Pentium 3 and 4, and have 512 MB and 768 MB RAM respectively (RAM can be upgraded soon however).

Is the Virtualization layer small enough to run itself and a Linux OS effectively? Will performance be acceptable (50% CPU overhead for every operation isn't acceptable)? Does it leave enough RAM for the Linux OS? Is this even feasible?

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Based on your description I have to tell you that you're not going to gain anything by going down that road. Quite the contrary, you will merely create a whole new set of problems while suffering even worse performance than you have now. Your time would be better spent ensuring you have a decent backup strategy that will allow you to do cold metal restores. – John Gardeniers Mar 14 '11 at 23:52
@John These systems aren't CPU loaded at all. Various spikes in the number of active user's haven't even been noticed on CPU graphs. Really the only limiting factor is the pitiful amount of RAM that's in these boxes. – TheLQ Mar 15 '11 at 0:19
the CPU load is only one part of the equation. I would suggest the RAM is your big issue right now but the CPU will need to do a lot more if you virtualise. Remember, PII and P4 were never designed for that sort of usage. Personally I'd just buy a reasonable workstation and use that until you can get a new server and keep the current machine(s) as emergency backups. – John Gardeniers Mar 15 '11 at 0:56
@John I know, but I really need this to work. As hardware scales rapidly I need to be able to move and change roles with limited downtime. Reinstalling takes way to much time and work. But your right, PIII's were never designed for this usage, which is why soon I will be testing on another box from this era with a PIII. I will get back to this question with the results soon. – TheLQ Mar 15 '11 at 13:39
In a situation like this you may be stuck with 32bit OS's. Those old PIII's don't support VT-d. Best not to fiddle with what's currently working even if it's a tad slow. – Matt Nov 20 '13 at 0:46
up vote 3 down vote accepted

On machines of that age, you will only be able to run very, very old versions of ESX (not ESXi). v2 or thereabouts, if you can find it. And ESX had a footprint of around 128-256Mb around that time, so you won't be able to do much with it when it is installed.

I once had ESX running on a Dual PII 400 with 512Mb of RAM. It wasn't pretty, but no virtualisation was that pretty back then.

You'll also miss out on all the virtualisation technologies that newer processors have.

Personally I would definately go ahead with it (if you can find a copy of ESX that old), but make sure that it's not in production until you're happy with how it performs and its reliability.

What I would definately do is scrounge around until I could afford a bare-bones PC with an i7 processor and a motherboard that is on the VMWare HCL. Depending on where you live in the world, this could range in price from $400 to $1000, and would be worth every cent.

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Is there a strict supported processor list that prevents ESXi from running on hardware this old? And if its going to consume that much RAM, I can always upgrade to get more room to play with. RAM is something I can afford – TheLQ Mar 14 '11 at 22:36
@TheLQ - yes, there is. ESXi has a VERY strict HCL and it will refuse to install on equipment that isn't on the list. It also REQUIRES 64-bit processors (and I think they need to have the VT extensions), so you're totally out of luck on ESXi. The newer versions of ESX might be worth playing with, but your best bet will be a yea-olde version of ESX. – Mark Henderson Mar 14 '11 at 22:38
@Mark This complicates things... Any version number you can recommend? – TheLQ Mar 14 '11 at 22:40
@TheLQ, it was about 6 years ago when I did this, so I suspect it was ESX v2.5 – Mark Henderson Mar 14 '11 at 23:00
@Mark Can't find a version that old (Oldest was in the 3.0 era) that's downloadable. And even then its sounds questionable. This hardware is from early 2000s, any strict HCL is going to kill it. I guess I'll investigate Xen server – TheLQ Mar 14 '11 at 23:13

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