[CentOS] Question about storage for virtualisation

Nicolas Ross
Tue, 26 Jun 2012 01:05:17 -0000

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 :
http://blog.mattbrock.co.uk/2012/02/12/virtualisation-with-kvm-and-lvm-on-centos-6-via-the-command-line/

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
partition.

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 !