Hi Xavi,
> On Mon, Oct 17, 2022 at 1:03 PM Stefan Solbrig <stefan.solbrig at ur.de
<mailto:stefan.solbrig at ur.de>> wrote:
> Dear all,
>
> I was doing some testing regarding to GlusterFS link files (as they are
created by a "move" operation). According to this document:
https://www.gluster.org/glusterfs-algorithms-distribution/
<https://www.gluster.org/glusterfs-algorithms-distribution/> If a link
file is missing, it should be created after accessing the file.
> However, I don't see this behaviour. If I delete (by hand) a link file
on the brick, the file is still accessible, but the link file is never
recreated. I can do an "open" or a "stat" on the file
without getting an error, but the link file is not created.
> Is this the intended behaviour? Or am I misunderstanding the above
mentioned document?
>
> You shouldn't access or modify the backend filesystems manually, you
can accidentally create unexpected problems if you don't fully understand
what you are doing.
>
> That said, most probably the access to the file is still working because
Gluster is using its cached information to locate the file. If the client mount
is restarted, probably the file won't be accessible anymore unless you
disable the "lookup-optimize" option (and this should recreate the
link file).
>
> Regards,
>
> Xavi
Thanks for the quick reply! Maybe I should explain better my motivation for the
above mentioned experiments. I have a large production system running GlusterFS
with almost 5 PB of data (in approx 100G of inodes). It's a distributed-only
system (no sharding, not dispersed). In this system, the users sometimes
experience the problem that they cannot delete a seemingly empty directory. The
cause of this problem is, that the directory contains leftover link files, i.e.
dht link files where the target is gone. I haven't identified yet why this
happens and I don't have a method to provoke this error (otherwise I would
have mentioned it on this list already.) But my quick & dirty fix is, to
delete these leftover link files by hand. (These leftover link files are not
being cleaned up by a "rebalance".)
The reason for my experiments with link files is: what happens if for some
reason I accidentally delete a link file where the target still exists?
In the experiments (not on the production system) I also tried umounting and
remounting the system, and I already tried setting "loopup-optmize =
off". It doesn't affect the outcome of the experiments.
best wishes,
Stefan
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