<div dir="ltr">If your topology is like the following: HDD -> ZFS (ZVOL) -> DRBD -> XFS then I believe it should make sense to always mount at the DRBD level and not at the ZVOL level which happens to be the underlying blockdev for DRBD.</div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Sep 6, 2017 at 12:28 PM, Jan Schermer <span dir="ltr"><<a href="mailto:jan@schermer.cz" target="_blank">jan@schermer.cz</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Not sure you can mount snapshot (I always create a clone).<br>
However I never saw anything about “drbd” filesystem - what distribution is this? Apparently it tries to be too clever…<br>
Try creating a clone and mounting it instead, it’s safer anyway (saw bug in issue tracker that ZFS panics if you try to write to the snapshot or something like that…)<br>
<br>
Other than that - yes, this should work fine.<br>
<span class="HOEnZb"><font color="#888888"><br>
Jan<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
<br>
> On 6 Sep 2017, at 13:23, Gionatan Danti <<a href="mailto:g.danti@assyoma.it">g.danti@assyoma.it</a>> wrote:<br>
><br>
> On 19/08/2017 10:24, Yannis Milios wrote:<br>
>> Option (b) seems more suitable for a 2 node drbd8 cluster in a primary/secondary setup. Haven't tried it so I cannot tell if there are any clurpits. My only concern in such setup would be if drbd corrupts silently the data on the lower level and zfs is not aware of that.Also, if you are *not* going to use live migration, and you can affort loosing some seconds of data on the secondary node in favor of better performance in the primary node, then you could consider using protocol A instead of C for the replication link.<br>
><br>
> Hi all,<br>
> I "revive" this old thread to let you know I settled to use DRBD 8.4 on top of ZVOLs.<br>
><br>
> I have a question for anyone using DRBD on top of a snapshot-capable backend (eg: ZFS, LVM, etc)...<br>
><br>
> When snapshotting a DRBD block device, trying to mount it (the snapshot, not the original volume!) results in the following error message:<br>
><br>
> [root@master7 tank]# mount /dev/zvol/tank/vol1\@snap1 /mnt/<br>
> mount: unknown filesystem type 'drbd'<br>
><br>
> To successfully mount the snapshot volume, I need to specify the volume filesystem, for example (the other options are xfs-specific):<br>
><br>
> [root@master7 tank]# mount -t xfs /dev/zvol/tank/vol1\@snap1 /mnt/ -o ro,norecovery,nouuid<br>
><br>
> Is that the right approach? Or I am missing something?<br>
> Thanks.<br>
><br>
> --<br>
> Danti Gionatan<br>
> Supporto Tecnico<br>
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</div></div></blockquote></div><br></div>