James G. Sack (jim) wrote:
Andrew Lentvorski wrote:
Gus Wirth wrote:
I think what you want is VMware. Do all your computing in a virtual
machine and when you break something roll back to the last known good
snapshot. You can keep lots of snapshots and even branch them for
different tasks.
OpenSolaris also has a nice feature which takes a ZFS snapshot of your
system before upgrading, upgrades it, and then switches over to the new
system. You can revert back to the old snapshot, however, if you want.
How expensive are these snapshots -- are they COW?
All of ZFS is copy-on-write all the time. So, snapshots are very fast.
Presumably you need
to quiesce the fs (and things like databases) before the snapshot, eh?
No, the copy-on-write takes care of that as long as the system requests
a proper synchronous barrier. Although, you shouldn't really be mixing
your system volumes with your application volumes.
I assume VMware snapshots are a different animal -- do their snapshots
require a restart, maybe?
No. VMware snapshots are of the *entire* system--including RAM. Thus,
when you revert a "snapshot" you are reverting to an actual earlier
position in time.
VMWare snapshots tend to be painfully slow.
-a
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