[CentOS] Virtualization as cheap redundancy option?

Sat Jun 26 12:43:30 UTC 2010
Arun Khan <knura9 at gmail.com>

On Fri, Jun 25, 2010 at 6:34 PM, Emmanuel Noobadmin
<centos.admin at gmail.com> wrote:
> I'm wondering if virtualization could be used as a cheap redundancy
> solution for situations which can tolerate a certain amount of
> downtime.

Absolutely.  I use the Linux KVM as my virtualization platform.   It
is just not redundancy but also better utilization of your hardware
and saving installation/configuration time by creating templates.

For example, at a couple of client locations, I  have 4 DNS/openLDAP
servers in production  (2 VMs each on 2 different hosts) per location.
  I did the initial install for one VM,  the configured DNS + LDAP
services, tested them and put them in production.  To replicate,  I
simply copy the VM image on to the other host,  reconfigure the
services in the guest VMs to be secondary servers.  The secondary DNS
and  LDAP servers are synced with the primary using their own internal
mechanism for replication.

Now I can use the same image file as a template for any other client
that wants these services in their IT infra.

Do a minimal install of  the host OS (takes less time), make sure it's
clock is in sync with a reliable NTP server.  The keyword is "minimal"
- only those packages that are needed to support virtualization.
Copy the necessary VM files; change the client specific info like
domain names, user entries and the "DNS/Directory server" is
operational within an hour.

-- Arun Khan