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Network based raid-1 DRBD


Myatu
20-07-2010, 10:24
Quote Originally Posted by ictdude
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
19-07-2010, 23:30
Quote Originally Posted by 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).
Myatu so you are talking about this software ? http://en.wikipedia.org/wiki/Unison_(file_synchronizer)

ictdude
19-07-2010, 23:25
Quote Originally Posted by 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.
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
19-07-2010, 17:21
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
19-07-2010, 15:44
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
19-07-2010, 09:03
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