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

[Tomasz Chmielewski]

It seems to me that for some reason it's not possible to create a 
physical volume on a DRBD device (at least on my machine, that is).

Below, we can see that running "pvcreate" succeeds and than fails, then 
it succeeds again etc.:

# pvcreate -d -v /dev/drbd0
     Set up physical volume for "/dev/drbd0" with 976544952 available 
sectors
     Zeroing start of device /dev/drbd0
   Physical volume "/dev/drbd0" successfully created

# pvcreate -d -v /dev/drbd0
     Wiping cache of LVM-capable devices
     Set up physical volume for "/dev/drbd0" with 976544952 available 
sectors
     Zeroing start of device /dev/drbd0
   Failed to write physical volume "/dev/drbd0"

# pvcreate -d -v /dev/drbd0
     Set up physical volume for "/dev/drbd0" with 976544952 available 
sectors
     Zeroing start of device /dev/drbd0
   Physical volume "/dev/drbd0" successfully created


Running vgcreate fails:

# vgcreate san2_data /dev/drbd0
   No physical volume label read from /dev/drbd0
   /dev/drbd0 not identified as an existing physical volume
   Unable to add physical volume '/dev/drbd0' to volume group 'san2_data'.



This is the setup used:

encrypted /dev/sdb -> unencrypted /dev/mapper/san2_crypt -> partition 
/dev/mapper/san2_crypt1 -> /dev/drbd0


I can create physical volume on /dev/mapper/san2_crypt2 (no DRBD) just fine.


The machine is running Debian Etch on a 2.6.23.12 kernel.

# lvm version
   LVM version:     2.02.07 (2006-07-17)
   Library version: 1.02.08 (2006-07-17)
   Driver version:  4.11.0


DRBD Version: 8.2.1 (api:86)


Any clues why this happens?


-- 
Tomasz Chmielewski
http://wpkg.org