Hi!

I just gave GlusterFS a try and experienced two problems. First some background:


-       I want to set up a file server with synchronous replication between 
branch offices, similar to Windows DFS-Replication. The goal is _not_ 
high-availability or cluster-scaleout, but just having all files locally 
available at each branch office.

-       To test GlusterFS, I installed two virtual machines in different 
locations, Ubuntu 12.04, with the GlusterFS 3.3 packages from the PPA.

-       Both machines shall be server and and client, and export the GlusterFS 
volume via samba.

-       I set up a file system in replica mode according to the quick start 
guide (except that I used ext4 instead of xfs for the brick, I had bad 
experiences with xfs)

-       I mounted the filesystem on both machines as localhost:/gv0, and shared 
the mount via samba.

At first it seemed to work fine (Copying files from/to the share, files appear 
instantly on the other host), until I did some robustness tests:

I severed the connection between the two hosts to provoke a split-brain 
scenario, just to see what happens. I expected both hosts to work, but on one 
of them the GlusterFS volume froze. After restarting the glusterfs-server 
service, it came back.

Then I intentionally created a conflicting file on each host.
After reconnecting the host, I got "Input/Output error" on both the conflicting 
file and the volume root inode. I found this 
http://blog.oneiroi.co.uk/linux/gluster-resolving-a-split-brain-in-a-replicated-setup/
  which fixed it for me, but having to manually fix the filesystem whenever a 
branch office link goes down does not feel very trustworthy. Is there some 
auto-conflict-resolving feature (last one wins, or renaming conflicting files)?

Then I took a look at the performance, and copied an ISO image (~ 700MB) to the 
filesystem. Worked fine, until I tried to md5sum it from both hosts. While the 
one node took a few seconds (what I expected), the other one took several 
minutes. Then I found out that it read the file over the WAN link from the 
distant host instead from itself. It should have had time enough (one hour) to 
replicate the file across both hosts...

(By the way, I also wanted to try geo-replication (which might suffice for my 
needs with a tight-enough schedule), but I was not able to create a volume with 
only one brick...

So I wonder: What did I do wrong?

Thanks

Martin


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