[CentOS] OT: Why VM?
gdr at gno.org
Fri May 27 21:29:19 UTC 2011
But taking the other side of the argument, here are two scenarios where
I *wouldn't* use virtualization (one could certainly enumerate more):
1. A production DB server or server cluster.
2. I've had services where I needed to maximize uptime. One option
I tried were VMs and being able to move the VM back and forth
between hosts. That might cover hardware failure, but I'd still
take outages when I needed to upgrade software in the VM. Moving
to a traditional HA solution on physical hardware means the outages
are now measured in seconds instead of minutes, and most of the time
are undetectable by the users.
I also tried services where the HA nodes are themselves VMs, but
was less than impressed with operational stability.
When CentOS 6 comes out, though, I'll be interested to see how (2)
behaves when it comes time to do a rolling upgrade from CentOS 5
(bring a node down, install and reconfigure C6 from scratch, rejoin
the cluster, have C6 take over the services, then upgrade the other
Thank god for test environments. And backups.
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