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Backup / Failover solution for Linux Colocated WebServers


I am looking for a reliable, low cost backup / failover solution for my 2 colocated dell webservers.

We have 2 servers, COLO1 is running SUSE9.0, Plesk7.5 and manages the client accounts. COLO2 is running REDHAT, Plesk7.5 and manages our business websites.

Our hosting company wants to make some offsite NAS space available, and for us to backup over to that. In event of failure this would mean re-imaging the server with a current snapshot and taking the most recent plesk dump and associated files. Our coders arent too happy with this, as they have a LOT of custom applications running on the server, and not sure about the best ways of sending these over to the NAS storage.

Their solution is to install a 3rd colocated server with 3 partitions, 1 running a linux distro and used for configuring, the 2nd partition would be a mirror of COLO1 and 3rd a mirror of COLO2, using RSYNC or similar daily to mirror / copy over the drives. In event of failure, boot order can be changed from partition 1 to 2 or 3, and with some IP fiddling, should bring a mirror of the broken server back online.

My question, is this possible or unlikely to work? Obviously reluctant to spend on a brand new server, only to find it does not work.

Plesk Licensing is also an issue, but they are considering moving to Webmin to avoid the issues.

Does this sound any good, or is the NAS storage a better, safer route, OR is there a better way?


3 Solutions
Do you plan to have 3 bootable Linux copies on 3rd server?
If yes, I see no problems with your schema. You also need to take a snapshot and to dump it to remote server (the same as with your NAS storage).
The only difference with NAS solution, is a faster recovery time (just bring up new server and go). Probably that can be done with custom boot menu of your 3rd server.
When you bring up your new server you are unable to backup remaining alive COLO server, just because you are running another system. Some software justification is required in that case.

Also note, that your solution is a mirroring, not a backup solution. With backup you normally have several snapshots for different days. Suppose someone (hacker or worker) broke your system 2 days ago, then you are unable to revert to previous stable state because you don't have a backup. That's why backup is better. Or even better to have both backup schemas.
BTW. How much disk is used on your COLO1 and COLO2 and how much do you plan to have on 3rd server?
Sounds like a good time to start adopting Xen to me. v3 is rock solid, and makes things so much easier. You can snapshot your VM's, rsync the backups somewhere secure, and rollback in a matter of minutes with negligible data-loss. Also means you don't have to waste loads of money on expensive hardware that you really don't need.
Gabriel OrozcoSolution ArchitectCommented:

virtual servers can help, and you can make every server a mirror of the other server.

in my case, I would recommend better "linux vservers" because they run with a lot less resources than Xen, and are fully transportable also, like in Xen.

I'm using vservers day to day and performance in old hardware is a big plus for us.

with this, maybe you need to add extra storage and maybe some more RAM for the case of one server failing and having the other server running both instances.

you can do mirroring using rsync over ssh to be secure

this of course is not a backup solution. this is a high availability solution which still needs backup in order to be achieved

So in general, I think Nopius and alextoft said it all. I would use Virtual Servers, it's all.
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