[CentOS] Question about storage for virtualisation

Tue Jun 26 01:05:17 UTC 2012
Nicolas Ross <rossnick-lists at cybercat.ca>

Hi !

I'm about to deploy a new server that will host several virtual host for 
mainly website hosting purposes. My server will be a Xeon 3440 or 3450 
with 32 gigs of ram (the max of that board). So I will have 8 logical 
cores. At the moment, I don't know how many vms I will have, in the 
order of 5 or 6.

I am quite new to managing VMs, I did play alot with them over the 
course of the last couple of weeks. I used kvm to startup and manage my 
vms and my main source of info was this blog entry : 

I have some general questions about VM.

If I set vcpu let's say to 2-3 for a single vm, does this mean that 
those CPU are dedicated to that vm or many vm can share the same 
physicial cpus ?

So, I was wondering what's the best for managing storage for VMs ? I see 
mostly recomandations for LV for storing VM's disks. It seem to helps to 
create snapshots for backup purposes. Is this the fastest way of 
creating backups ? And will data access be faster that if I use regular 
files ?

In my case, the "main" setup of each vm is rather simple. The minimal 
OS, updates, my own httpd, my own php a couple of other packages. So 
restoring a VM from scratch can take less than an hour. So I was 
thinking of not taking snapshot of the whole VM and only sync the data 

As for the guest paritions, I am accustomed of separating my servers 
disks with separate /, /usr, /var, /home and /data partitions. I can't 
recall today why I started doing this, 15 years ago, but I still like it 
that way and continue to do so. Do I still "need" to do this with VMs ?

Thanks for the help !