[DRBD-user] configuring 2 services on 2 hosts

Felix Frank ff at mpexnet.de
Fri Jan 7 09:23:30 CET 2011

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

>  With DRBD as a PV on top of MD, you can still allocate out that PV
> incrementally and resize the individual LVs as needed.  If you put in
> bigger disks, you can just add another partition for the new space,
> create a new PV, and concatenate the exist VG in linear mode with the
> new PVs.  Then the existing VG is now made up of 2 PVs on the same disk
> in linear mode.  Space management flexibility here doesn't shouldn't
> play into this decision as having LVM instanced twice in the block
> device doesn't add any new flexibility over a single instance.

Careful, though. If there's anything I got hammered in during DRBD
Total, it was *never* to create VGs, RAID0s etc. out of multiple DRBD
devices. That's creating a management nightmare, because you'd introduce
a requirement to always have these DRBDs primary on the same node.

If, on the other hand, the underlying md is extended using additional
hardware, doing pvresize on top of DRBD should be no problem at all.


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