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Re: [PLUG] Need Troubleshooting Advice: Disk Errors in Virtual Machines
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On Wednesday 22 September 2010 12:51:22 am Lee Marzke wrote:
> On 09/21/2010 08:00 PM, Casey Bralla wrote:
> > On Tuesday 21 September 2010 7:25:26 pm Lee Marzke wrote:
> >> On 09/21/2010 06:04 PM, Casey Bralla wrote:
> >>> I've got a weird problem which I hope somebody here can help me figure
> >>> out.
> >>>
> >>> I'm running about a dozen virtual machines (mostly web servers) on a
> >>> triple- core AMD system running Debian Lenny (ie: "Stable"). Each of
> >>> the virtual machines is also running Debian Lenny.
> >>>
> >>> I am having repeated disk errors on the Virtual Machines, but no disk
> >>> errors on the host machine. These disk errors often cause a Kernel
> >>> Panic within the VM, or otherwise crash the web server on the VM.
> >>
>
> 64Mb per VM ? That seems way, way too low. The Debian
> recommendation is 256Mb + what is needed by apache.
>
> Is there some reason you have a dozen VM's ? Shouldn't apache handle
> hundreds of websites on a single VM ?
> Can I assume you have thousands of websites then ?
>
Since these are solely used for Web Servers with VERY low traffic (~20
hits/day), and I don't do any X-windows, it can actually run in 32 MBytes.
The swap usage of the VMs seems minimal.
> If you really have that many VM's you may need to re-think your
> architecture somewhat. I don't think a
> single disk system with 4GB of RAM is going to run a dozen VM's, that
> system is barely good for 4 servers
> servers. CPU usually doesn't matter, it's usually memory and then
> disk I/O that are the issue. Here
> I have a dual socket dual-core Opteron 265 SuperMicro MB, with 12GB
> RAM, running ESXi 4.0
You are probably correct. However, upgrading is a very remote possibility.
These sites are donated to several family and friends. I can't add RAM
without spending $ hundreds, which the family budget won't allow.
Still, even if I were completely overloading the server, I would expect to see
PERFORMANCE issues, not crashes. In fact, performance seems pretty good.
I may have to change the architecture as you suggested and combine several
sites on a single VM, but I was hoping to simplify (Ha! That's working well,
isn't it?!? <grin>) my setup by giving each customer and web page/blog a
dedicated server.
I thought about switching to ESXi, but since BOTH VirtualBox & VMWare gave
very similar problems, there must be some other underlying cause. Also, ESXi
seems like a $$ solution, which my CFO (Mrs Bralla) won't allow.
> I just gave a talk Monday at VMware user group on moving to ESXi [2],
> that you might find interesting.
>
>
> Lee
>
> [1] http://plone.4aero.com/Members/lmarzke/thecus
>
> [2]
> http://plone.4aero.com/Members/lmarzke/vmug_esxi/moving-to-esxi-introductio
> n/presentation_view
Thanks for the suggestions! I'll check out your presentation.
--
Casey Bralla
Chief Nerd in Residence
The NerdWorld Organisation
http://www.NerdWorld.org
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