[DRBD-user] can't use LVM2 on drbd devices - "Failed to write physical volume"? [SOLVED]

Tomasz Chmielewski mangoo at wpkg.org
Thu Jan 10 17:40:28 CET 2008

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

Lars Ellenberg schrieb:

>> #cache/lvmcache.c:791       Duplicate PV 
>> Ndrdet3xirFKZfBIqtqjX1BAiXxW6dtd on /dev/drbd0 - using dm /dev/dm-95
> that is it, right there.
> pv label already detected on /dev/dm-95,
> (which is likely your de-crypted dm-crypt target?).
> you'd have to filter out that device in the lvm.conf.
> preferably, you'd have a filter that only accepts drbd,
> and rejects anything else.
> did you know about LVM_SYSTEM_DIR ?
> try this: copy your /etc/lvm to /etc/lvm.on-drbd,
> edit the lvm.conf there to place the cache there, too,
> or preferably: remove the cache, and disable it),
> edit the filter to something like a|^/dev/drbd|, r|.|,
> then
> ( export LVM_SYSTEM_DIR=/etc/lvm.on-drbd
>   pvcreate...
>   vgcreate...
> )
> if that works out, figure out how you can make
> that dm-XY device apear always as the same XY after reboot,
> then filter it out specifically.

Thanks for theory. I added "r|/dev/dm-2|" as a filter for LVM and 
created the volume just fine.

As of making /dev/dm-XY persistent - I'm trying to do it for some time, 
but the more I try, the more hopeless it looks to me ;)

udev creates its persistent rules by taking something that never 
changes: ethernet card's MAC address, disk's ID, fs label etc.

I've no idea how to make /dev/dm-XY for such a device static.

> your "partitioning" of the drbd changed the offset of the to-become pv,
> to something where lvm would normally not look.
> but if you want to go that route, rather partition the dm-XY below
> drbd, and put drbd on top of one of those.

Yes, that's what I'm trying to do.

Tomasz Chmielewski

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