[Myatu]

Myatu so you are talking about this software ? http://en.wikipedia.org/wiki/Unison_(file_synchronizer)

That's the one, yes. Unlike Rsync, it is bi-directional (though Unison is capable of using Rsync if you wish).

This is especially useful in a load balanced environment, ie., where both servers are active and may write things to disk (the alternative to that is shared disk space like NFS, SAN, etc - but that re-introduces a single point of failure unless that too is mirrored on separate servers; more £££!).

Conflict handling (in case the same file was modified on two [or more] systems) can be automated as well, by selecting one as a "prefered" server (ie., a "master").

[ictdude]

It depends on what you wish to mirror really. If it's just a webserver where the stored data doesn't change much, Unison is more efficient (which is what I use between VMs). If you're dealing with larger and more frequently changing data, then DRBD is the way to go -- however I would personally use a 2nd NIC dedicated to DRBD (MGs used to have this if I recall correctly).

Myatu so you are talking about this software ? http://en.wikipedia.org/wiki/Unison_(file_synchronizer)

[ictdude]

I've never tried it, but it seem to me that it only does file system synchronization, which is good for, for example, webserver.

When you want to synchronize a database, you'll still have to go through the MySQL (for example) methods for synchronization.

Well i found this artikel maybe its possible:

This post will show you how to create two MySQL servers that automatically replicate all their databases using DRBD.

http://www.wekadesign.co.nz/2010/01/...ntu-with-drbd/ That would be great. Gues first test it on a non-production servers first Nice for real load balancing.

[Myatu]

It depends on what you wish to mirror really. If it's just a webserver where the stored data doesn't change much, Unison is more efficient (which is what I use between VMs). If you're dealing with larger and more frequently changing data, then DRBD is the way to go -- however I would personally use a 2nd NIC dedicated to DRBD (MGs used to have this if I recall correctly).

[marks]

I've never tried it, but it seem to me that it only does file system synchronization, which is good for, for example, webserver.

When you want to synchronize a database, you'll still have to go through the MySQL (for example) methods for synchronization.

[ictdude]

I did found this useful tool http://www.drbd.org/home/what-is-drbd/

Looks really great to keep two servers in sync. For load balancing two servers.
Has somebody experience with this tool ? Looks really great.

More useful info: http://www.gridvm.org/drbd-lvm-gnbd-...iable-san.html