[Gluster-users] Initial sync

[Andreas Hollaus]

Hi,

I'm curious about how GlusterFS manages to sync the bricks in the initial phase, when
the volume is created or
extended.

I first create a volume consisting of only one brick, which clients will start to
read and write.
After a while I add a second brick to the volume to create a replicated volume.

If this new brick is empty, I guess that files will be copied from the first brick to
get the bricks in sync, right?

However, if the second brick is not empty but rather contains a subset of the files
on the first brick I don't see
how GlusterFS will solve the problem of syncing the bricks.

I guess that all files which lack extended attributes could be removed in this
scenario, because they were created
when the disk was not part of a GlusterFS volume. However, in case the brick was used
in the volume previously,
for instance before that server restarted, there will be extended attributes for the
files on the second brick which
weren't updated during the downtime (when the volume consisted of only one brick).
There could be multiple
changes to the files during this time. In this case I don't understand how the
extended attributes could be used to
determine which of the bricks contains the most recent file.

Can anyone explain how this works? Is it only allowed to add empty bricks to a volume?

 

-- 
Regards
Andreas