[DRBD-user] Partitioning /dev/drbd1

Dennis Jacobfeuerborn dennisml at conversis.de
Tue Mar 8 19:47:20 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.


On 03/08/2011 04:51 PM, Felix Frank wrote:
>
>> While kpartx works I'm wondering why it is necessary. I would expect
>> /dev/drbd1 to behave like a regular block device and the partitions to
>> show up if not after writing the new table then at least after a reboot.
>> Eventually I will probably go for an LVM setup but since this is
>> supposed to become part of a pacemaker cluster and I'd like to build
>> this up one step at a time I'd first like to get a filesystem on a
>> regular partition going before I add the LVM layer in between.
>
> Hi,
>
> while partitioning a partition is possible and rather straight-forward,
> it sure isn't standard practice.

I wasn't actually suggesting to create "partitions in partitions" I just 
wasn't aware that the drbd device nodes are partitions and not basic block 
devices (like i.e. the /dev/xvdN nodes that xen adds). That certainly 
explains the behavior I'm seeing.

> Besides, what do you expect from the kernel? Descending arbitrary levels
> of partitioning and adding nodes for the partitions thus found...by what
> system?
>
> Graphically: What major/minor numbers would you have associated with
> your third primary partition's first logical partition's second primary
> partition's first primary partition?
>
> Also, please make sure that replication actually works when you mount
> your "inner partitions" this way. I think it should, but I might be wrong.

I'm sure one could make this work but I don't intend to try it. I've seen 
people use logical LVM volumes as physical volumes for new volume groups 
which *seemed* to work though I didn't know for sure because I was too busy 
trying to get out of there. Always fun to see these kinds of 
M.C.Escher-esque topologies....as long as I don't have to maintain them :)

Regards,
   Dennis



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