[geeks] Virtual Machine Hosting

[Patrick Giagnocavo]

Shannon Hendrix wrote:
> On May 7, 2009, at 10:57 , Patrick Giagnocavo wrote:
> 
>> The CPU speed is usually not a problem, what will get you is disk access
>> of random reads/writes since the disks will be shared amongst all the
>> VMs.
> 
> I can verify this.
> 
> The company I work for uses a Xen machine for Subversion.
> 
> Disk access is a severe problems any time you hit the logs, which is
> pretty often with Subversion.
> 
> A lot of other apps suffer too.
> 
> Some places might have a solution for this, but several I've seen do not.
> 
> 
There are things you can do inside the VM, like mount noatime, give it
more RAM for disk cache, etc.

There are also things you can do outside the VM, like setting up a disk
slice to give the VM, etc. also (under linux you use LVM, under ZFS you
use zvols).  However the issue of disk contention remains.

I hope to be able to play around with iSCSI shortly, which should allow
for 2-4GB RAM of disk cache on the iSCSI server, might make things a
little better.

--Patrick