[lustre-discuss] ZFS w/Lustre problem

[Hans Henrik Happe]

I sounds like this issue, but I'm not sure what your dnodesize is:

https://github.com/openzfs/zfs/issues/8458

ZFS 0.8.1+ on the receiving side should fix it. Then again ZFS 0.8 is
not supported in Lustre 2.12, so it's a bit hard to restore, without
copying the underlying devices.

Cheers,
Hans Henrik

On 06.11.2020 21.23, Steve Thompson wrote:
> This may be a question for the ZFS list...
>
> I have Lustre 2.12.5 on Centos 7.8 with ZFS 0.7.13, 10GB network. I
> make snapshots of the Lustre filesystem with 'lctl snapshot_create'
> and at a later time transfer these snapshots to a backup system with
> zfs send/recv. This works well for everything but the MDT. For the
> MDT, I find that the zfs recv always fails when a little less than 1GB
> has been transferred (this being an incremental send/recv of snapshots
> taken a day apart):
>
> # zfs send -v -c -i fs0pool/mdt0 at 03-nov-2020 fs0pool/mdt0 at 04-nov-2020 | \
>     zfs recv -F backups/fs0pool/mdt0
> ....
> 12:11:18    946M   fs0pool/mdt0 at 04-nov-2020-01:00
> 12:11:19    946M   fs0pool/mdt0 at 04-nov-2020-01:00
> 12:11:20    946M   fs0pool/mdt0 at 04-nov-2020-01:00
> cannot receive incremental stream: dataset does not exist
>
> while if the data transfer is much smaller, the send/recv works. Since
> once I get a failure it is not possible to complete a send/recv for
> any subsequent day, I am doing a full snapshot send to a file; this
> always works and takes about 5/6 minutes for my MDT. When using zfs
> send/recv, the recv is always very very slow (several hours to get to
> the above failure point, even when using mbuffer). I am using custom
> zfs replication scripts, but it fails also using the zrep package.
>
> Does anyone know of a possible explanation? Is there any version of
> ZFS 0.8 that works with Lustre 2.12.5?
>
> Thanks,
> Steve

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