[Gluster-users] VM going down

Alessandro Briosi
Tue, 09 May 2017 14:59:51 -0000

Il 09/05/2017 16:10, Niels de Vos ha scritto:
> ...
>>> client from
>>> srvpve2-162483-2017/05/08-10:01:06:189720-datastore2-client-0-0-0
>>> (version: 3.8.11)
>>> [2017-05-08 10:01:06.237433] E [MSGID: 113107]
[posix.c:1079:posix_seek]
>>> 0-datastore2-posix: seek failed on fd 18 length 42957209600 [No
such
>>> device or address]
> The SEEK procedure translates to lseek() in the posix xlator. This can
> return with "No suck device or address" (ENXIO) in only one case:
>
>     ENXIO    whence is SEEK_DATA or SEEK_HOLE, and the file offset is
>              beyond the end of the file.
>
> This means that an lseek() was executed where the current offset of the
> filedescriptor was higher than the size of the file. I'm not sure how
> that could happen... Sharding prevents using SEEK at all atm.
>
> ...
>>> The strange part is that I cannot seem to find any other error.
>>> If I restart the VM everything works as expected (it stopped at
~9.51
>>> UTC and was started at ~10.01 UTC) .
>>>
>>> This is not the first time that this happened, and I do not see any
>>> problems with networking or the hosts.
>>>
>>> Gluster version is 3.8.11
>>> this is the incriminated volume (though it happened on a different
one too)
>>>
>>> Volume Name: datastore2
>>> Type: Replicate
>>> Volume ID: c95ebb5f-6e04-4f09-91b9-bbbe63d83aea
>>> Status: Started
>>> Snapshot Count: 0
>>> Number of Bricks: 1 x (2 + 1) = 3
>>> Transport-type: tcp
>>> Bricks:
>>> Brick1: srvpve2g:/data/brick2/brick
>>> Brick2: srvpve3g:/data/brick2/brick
>>> Brick3: srvpve1g:/data/brick2/brick (arbiter)
>>> Options Reconfigured:
>>> nfs.disable: on
>>> performance.readdir-ahead: on
>>> transport.address-family: inet
>>>
>>> Any hint on how to dig more deeply into the reason would be greatly
>>> appreciated.
> Probably the problem is with SEEK support in the arbiter functionality.
> Just like with a READ or a WRITE on the arbiter brick, SEEK can only
> succeed on bricks where the files with content are located. It does not
> look like arbiter handles SEEK, so the offset in lseek() will likely be
> higher than the size of the file on the brick (empty, 0 size file). I
> don't know how the replication xlator responds on an error return from
> SEEK on one of the bricks, but I doubt it likes it.
>
> We have https://bugzilla.redhat.com/show_bug.cgi?id=1301647 to support
> SEEK for sharding. I suggest you open a bug for getting SEEK in the
> arbiter xlator as well.

Well, I have not really clear the internals of gluster, but the arbiter
is not the host where the vm is running.
If gluster is aware of the arbiter, it should not look for data on that
brick beside metadata and "quorum".

Also the seek errors where there before when there was no arbiter (only
2 replica).
And finally seek error is triggered when the VM is started (at least the
one in the logs).


Alessandro
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