[DRBD-user] Partitioning a drbd device

Poyner, Brandon bpoyner at ccac.edu
Wed Mar 11 18:33:15 CET 2009

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

I can't answer if you're using drbd in a supported manner, but it
doesn't seem unusual to me.  If you give the drbd device to a virtual
machine to use as a raw block device, the virtual machine will treat it
like any other block device (e.g.: hard drive).  Back on the Dom0 host
if you examine the contents of the drbd device you'll see the partition
layout.  This matches what you're seeing except I don't know why your
swap partition isn't showing.

I take advantage of this to make disaster recovery backups of some
virtualized DomU Windows hosts (using Xen, not KVM).  I make an LVM
snapshot of the drbd device on the Dom0 host, use kpartx on the snapshot
to create the device files that map to the partitions inside the
snapshot, and then ntfsclone the partitions inside.  

Brandon Poyner
Network Engineer III
CCAC - College Office

> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com [mailto:drbd-user-
> bounces at lists.linbit.com] On Behalf Of Dominik Klein
> Sent: Wednesday, March 11, 2009 10:56 AM
> To: drbd-user at lists.linbit.com
> Subject: [DRBD-user] Partitioning a drbd device
> Hi
> I'm looking at kvm virtualisation and the pretty nice virt-manager.
> Thanks Florian for making me look into it! :)
> So while setting up a kvm on top of a drbd device, the setup process
> partitioned the drbd device into root and swap partitions.
> # fdisk -l /dev/drbd2
> Disk /dev/drbd2: 32.2 GB, 32211234816 bytes
> 255 heads, 63 sectors/track, 3916 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Disk identifier: 0x09fffa0f
> Device Boot      Start         End      Blocks   Id  System
> /dev/drbd2p1               1        3916    31455238+  83  Linux
> I talked to Brian Hellman on IRC and he (quoting Lars) sort of said it
> was not possible to partition a drbd device so I am pretty confused
> here. Didn't I just do that?
> So what I'd like to know is whether this is a supported setup and
> considered save to do/use.
> Searching for "partition drbd" was not exactly helpful as you might
> imagine.
> Thanks in advance
> Dominik
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