[CentOS] "multi-boot" drive partitioning

Les Mikesell lesmikesell at gmail.com
Tue Dec 18 17:42:45 UTC 2007


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 at gmail.com




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