[Gluster-users] Failed rebalance resulting in major problems

[Justin Dossey]

Shawn,

I had a very similar experience with a rebalance on 3.3.1, and it took
weeks to get everything straightened out.  I would be happy to share the
scripts I wrote to correct the permissions issues if you wish, though I'm
not sure it would be appropriate to share them directly on this list.
 Perhaps I should just create a project on Github that is devoted to
collecting scripts people use to fix their GlusterFS environments!

After that (awful) experience, I am loath to run further rebalances.  I've
even spent days evaluating alternatives to GlusterFS, as my experience with
this list over the last six months indicates that support for community
users is minimal, even in the face of major bugs such as the one with
rebalancing and the continuing "gfid different on subvolume" bugs with
3.3.2.

Let me know what you think of the Github thing and I'll proceed
appropriately.


On Tue, Nov 5, 2013 at 9:05 PM, Shawn Heisey <gluster at elyograg.org> wrote:

> We recently added storage servers to our gluster install, running 3.3.1
> on CentOS 6.  It went from 40TB usable (8x2 distribute-replicate) to
> 80TB usable (16x2).  There was a little bit over 20TB used space on the
> volume.
>
> The add-brick went through without incident, but the rebalance failed
> after moving 1.5TB of the approximately 10TB that needed to be moved.  A
> side issue is that it took four days for that 1.5TB to move.  I'm aware
> that gluster has overhead, and that there's only so much speed you can
> get out of gigabit, but a 100Mb/s half-duplex link could have copied the
> data faster if it had been a straight copy.
>
> After I discovered that the rebalance had failed, I noticed that there
> were other problems.  There are a small number of completely lost files
> (91 that I know about so far), a huge number of permission issues (over
> 800,000 files changed to 000), and about 32000 files that are throwing
> read errors via the fuse/nfs mount but seem to be available directly on
> bricks.  That last category of problem file has the sticky bit set, with
> almost all of them having ---------T permissions.  The good files on
> bricks typically have the same permissions, but are readable by root.  I
> haven't worked out the scripting necessary to automate all the fixing
> that needs to happen yet.
>
> We really need to know what happened.  We do plan to upgrade to 3.4.1,
> but there were some reasons that we didn't want to upgrade before adding
> storage.
>
> * Upgrading will result in service interruption to our clients, which
> mount via NFS.  It would likely be just a hiccup, with quick failover,
> but it's still a service interruption.
> * We have a pacemaker cluster providing the shared IP address for NFS
> mounting.  It's running CentOS 6.3.  A "yum upgrade" to upgrade gluster
> will also upgrade to CentOS 6.4.  The pacemaker in 6.4 is incompatible
> with the pacemaker in 6.3, which will likely result in
> longer-than-expected downtime for the shared IP address.
> * We didn't want to risk potential problems with running gluster 3.3.1
> on the existing servers and 3.4.1 on the new servers.
> * We needed the new storage added right away, before we could schedule
> maintenance to deal with the upgrade issues.
>
> Something that would be extremely helpful would be obtaining the
> services of an expert-level gluster consultant who can look over
> everything we've done to see if there is anything we've done wrong and
> how we might avoid problems in the future.  I don't know how much the
> company can authorize for this, but we obviously want it to be as cheap
> as possible.  We are in Salt Lake City, UT, USA.  It would be preferable
> to have the consultant be physically present at our location.
>
> I'm working on redacting one bit of identifying info from our rebalance
> log, then I can put it up on dropbox for everyone to examine.
>
> Thanks,
> Shawn
>
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org
> http://supercolony.gluster.org/mailman/listinfo/gluster-users
>



-- 
Justin Dossey
CTO, PodOmatic
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://supercolony.gluster.org/pipermail/gluster-users/attachments/20131106/635a6200/attachment.html>