[Gluster-users] How does replication work?

Daniel Maher dma+gluster at witbe.net
Tue Sep 8 16:02:08 UTC 2009

Alan Ivey wrote:

> Thanks for the reply Daniel. I've been experimenting with it this morning and specifically the auto-healing feature. I've found out that it really only auto-heals when I ls the client directory. That's the only time I was able to get the second server to catch up with the files that were written while the second server was down. I was hoping that any operating performed on the client would cause the second server to catch all the way up to the second server, but creating a new file replicated it on both machines, but not the files created in the meantime.
> So, my question now is, what operations cause the auto-healing to execute? I was only able to get it to catch up when running ls on the client-side. I'm envisioning using this as HA-NFS, and so if I want all servers to always have the correct files and perms, should I create a cron to run ls on the client directory every minute?
> According to the documentation at http://www.gluster.com/community/documentation/index.php/Understanding_AFR_Translator#Frequently_Asked_Questions , it looks like indeed running an ls is a sure-fire way to self-heal all directories. Without this intervention, what glusterfs client commands will cause this to happen?
> Thanks again!

Well, auto-healing only needs to happen if one or more of the storage 
bricks was inaccessible - otherwise files stay synchronised via 
replication as normal.

If you're considering running a process in order to trigger self-heal 
all the time, then presumably something is really wrong with your 
network, and you should probably address that before trying to get 
Gluster going. :)

Daniel Maher <dma+gluster at witbe.net>

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