Frank Cox wrote:
This was to be my point exactly ... what good does a machine that can
boot up into a file server with last months data or a web server with
last months data be if the current server just died?
If you have a backup system in place with the ability to push certain
directories onto this machine, then maybe. Otherwise, this seems fairly
pointless.
All of the live data gets backed up every night to an offsite fileserver.
It will take a lot less time to copy the live data from the backup than it
will to set up a new computer and then copy the live data from the backup.
It probably won't help in this case, but what has worked pretty well for
me has been to use swappable drives and software raid1 on critical
servers, and keep a spare chassis around. If a single drive fails (the
most likely failure), you just replace it and resync at a convenient
time. If a motherboard or power supply fails, you move the drives to
the spare server and are back with a few minutes of downtime and no data
loss. You still need backups to cover some less likely modes of failure
(like an admin typing 'rm -f *' in the wrong place...). This doesn't
provide automatic failover or 100% uptime, but it avoids the complexity
and additional failure modes that other schemes can introduce. And a
nice side effect is that you can do major upgrades by building your next
version on the spare box, swap the new disks into place, change the IP
address (you may have to clear your router's arp table here) and be
running again in the time it takes to reboot. Or, if you want to clone
a server you can just pull one of the mirrored drives and resync to a
new mate on both machines, changing the hostname and IP address on one
of them - and both can be running while the resync proceeds.
--
Les Mikesell
lesmikesell@xxxxxxxxx
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