[DRBD-user] parted to move a partition DRBD uses as a backing device

Nelson Hicks nelsonh at socket.net
Thu Jul 31 17:05:16 CEST 2014

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


I haven't done exactly what you're doing, but it seems like you will
need to at least detach the local backing device in DRBD before moving
its partition (I think parted will need all access locks cleared from
the partition before the move step) and reattach it after moving it.
DRBD cares about the position of its meta-data relative to the partition
end, so as long as you keep the partition size the same, I think it will
reattach without complaint. I have used this procedure to move the
backing device to another partition of the same size.

Be sure to follow the steps in the DRBD guide for resizing resources
when you get to the part of the process where you're actually extending
the size of the partitions. DRBD will need to know that the partition
size has changed so it can move its meta-data (or the meta-data itself
may need to be moved manually).

http://www.drbd.org/users-guide/s-resizing.html
http://www.drbd.org/users-guide-8.3/s-resizing.html

-- 
Nelson Hicks
Network Operations
SOCKET
(573) 817-0000 ext. 210
nelsonh at socket.net




On Thu, 2014-07-31 at 09:01 -0400, Digimer wrote:
> On 31/07/14 04:50 AM, Felix Frank wrote:
> > On 07/31/2014 12:49 AM, Digimer wrote:
> >>
> >>    However, it lists in the docs that the "FS" needs to support this, and
> >> well, DRBD is not an FS.
> >
> > Weird.
> >
> > FWIW, I read that as "do this only if the data on the partition cares
> > not about absolute positions of its blocks on the device", i.e. relative
> > addressing in the filesystem.
> >
> > (So XFS would break if I tried that? Sounds specious. Perhaps the
> > document refers to moving data while it's mounted?)
> >
> > Either way, you can likely apply the documentation to the *content* of
> > the DRBDs, as though that additional block layer weren't present.
> >
> > A shame that you gain only 300G, otherwise I'd advise to take this
> > chance to move to LVM ;-)
> >
> > Regards,
> > Felix
> 
> I use clustered LVM with DRBD as the PVs. When I tried to use LVM under 
> DRBD as well, it got complicated.
> 
> To be honest, I've never needed to do this in production, but I wanted 
> to document the process in case it is ever needed.
> 
> So I suppose, if no one knows for sure, I can try moving the partition 
> and see what happens. It's a test/dev machine so the data on it is 
> disposable (just clvmd + gfs2 + a pair of test VMs).
> 
> Can I assume that you don't think DRBD will care about absolute positions?
> 






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