[DRBD-user] DRBD -> LVM -> Xen -> non-clustered-filesystem?

James Vanns james.vanns at framestore-cfc.com
Fri Nov 24 18:28:02 CET 2006

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


This maybe slightly off-topic as I am unsure if this is a DRBD problem
or not (I am using LVM fine locally...)

OK, so now I can't create an LVM PV on a DRBD device:

[root at jimmy ~]# pvcreate -M 2 --setphysicalvolumesize 150G -v /dev/drbd0
    Loaded external locking library /usr/lib/liblvm2clusterlock.so
    Wiping cache of LVM-capable devices
    Wiping internal VG cache
  Device /dev/drbd0 not found (or ignored by filtering).

It (/dev/drbd0) is not ignored by filtering (its explicitly 'accepted'
in lvm.conf just to be sure) and it does exist:

[root at jimmy ~]# ls -lath /dev/drbd?
brw-r----- 1 root disk 147, 1 Nov 24 16:05 /dev/drbd1
brw-r----- 1 root disk 147, 0 Nov 24 13:46 /dev/drbd0

[root at jimmy ~]# ls -lath /sys/block/drbd?
/sys/block/drbd1:
total 0
drwxr-xr-x  4 root root    0 Nov 24 17:25 .
-r--r--r--  1 root root 4.0K Nov 24 17:25 removable
-r--r--r--  1 root root 4.0K Nov 24 17:25 size
-r--r--r--  1 root root 4.0K Nov 24 17:25 stat
--w-------  1 root root 4.0K Nov 24 17:25 uevent
-r--r--r--  1 root root 4.0K Nov 24 16:05 range
lrwxrwxrwx  1 root root    0 Nov 24 16:05 subsystem -> ../../block
-r--r--r--  1 root root 4.0K Nov 24 16:05 dev
drwxr-xr-x 27 root root    0 Nov 24 16:05 ..
drwxr-xr-x  2 root root    0 Nov 24 16:05 holders
drwxr-xr-x  2 root root    0 Nov 24 16:05 slaves

/sys/block/drbd0:
total 0
drwxr-xr-x  4 root root    0 Nov 24 17:23 .
-r--r--r--  1 root root 4.0K Nov 24 17:23 range
-r--r--r--  1 root root 4.0K Nov 24 17:23 removable
-r--r--r--  1 root root 4.0K Nov 24 17:23 size
-r--r--r--  1 root root 4.0K Nov 24 17:23 stat
lrwxrwxrwx  1 root root    0 Nov 24 17:23 subsystem -> ../../block
--w-------  1 root root 4.0K Nov 24 17:23 uevent
-r--r--r--  1 root root 4.0K Nov 24 16:16 dev
drwxr-xr-x 27 root root    0 Nov 24 16:05 ..
drwxr-xr-x  2 root root    0 Nov 24 13:46 holders
drwxr-xr-x  2 root root    0 Nov 24 13:46 slaves

Any ideas?

Jim

On Thu, 2006-11-23 at 23:13 +0100, Håkan wrote:
> James Vanns wrote:
> > What are your thoughts on the following setup?
> >
> > 2x physical nodes - identical
> > DRBD latest 'pre' 0.8 source
> > Fedora Core 6 host OS/dom0 (on both nodes)
> > Crossover cable between the two nodes with 10.0.0.1, 10.0.0.2
> > respectively purely for DRBD chatter.
> > Metadata (of DRBD) stored on a separate disk on each machine
> > (/dev/sda5).
> > DRBD 'source' drive is /dev/sdb and target drive is /dev/drbd0
> >   
> This is almost exactly my setup as well. Seems reasonable.
> 
> 
> 
> > ...Therefore Xen1 will never write to the same LV as Xen2. But then there
> > is the question of LVM meta data etc. logs and caches etc. of all these
> > layers - how do you think DRBD will handle it without the use of OCFS or
> > GFS as the choice of FS on the Xen LV drives
> >   
> DRBD handles it just fine, since it's working on a block device layer. I
> use ext3 with good results.
> I compile my own LVM, device-mapper and cluster suite, to get it the way
> i want it, with clvmd and all. This ensures that there will be no
> problem with meta data and such.
> DRBD does a good job here, and it works quite good with the new pre6.
> Nothing much to add there.
> My setup works well with migration, which is why I use drbd in the first
> place.
> 
> 
> /Håkan
> 
-- 
James Vanns
Systems Programmer
Framestore CFC Ltd.





More information about the drbd-user mailing list