RAID drives across a network

[clan184]

I'm upgrading a server and I want to have a backup server system at a remote location connected to the main server by VPN. The idea is that it will pick up seamlessly if the main server goes down.
Can I set up mirrored RAID drives which are on different systems ??

[jasonlambert]

AFAIK, no you cannot. you would need something like Network Attached Storage, which is basically a box with a load of hard disks in it, and not much else.

You could look at writing a script to copy your files, using a program like rsync, or depending on what exactly the server is doing (eg, databases, print sharing etc) you may beable to do something specific for each of the services.

Jason

[Dolda2000]

Well, technically speaking, you can do that. Linux has support for a network block device. You'll need to compile a kernel with support for that and check out how to set it up (I've never used it myself). Then you should be able to create a RAID1 array with a physical drive and the NBD.

However, I have no idea how well this works (with caching, etc.), and you won't be able to mount the filesystem on the back-up server until the main server is down, and performance is likely to be terrible.

All in all, I'd recommend against that method. There may well be other methods of doing it that I don't know of, though.

One alternative method could be to let a third server just act as a file server, and then let both those servers run NFS off of that one.

[sarumont]

You could also setup an rsync server to keep your server up to date with the backup (or vice-versa). This could be a cron job that syncs the whole drive every x minutes.

http://www.rsync.samba.org