[DRBD-user] DRBD-LVM sandwich questions

Gianluca Cecchi gianluca.cecchi at gmail.com
Wed Jul 22 07:58:03 CEST 2009

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

On Tue, Jul 21, 2009 at 11:49 PM, Dmitry S. Makovey<dmitry at athabascau.ca> wrote:
> Hi everybody,
> we're running LVM-DRBD-Xen-LVM sandwich on our boxes and got an interesting
> question:
> Now the actual questions:
> 1. why did fdisk report /dev/system/lv1 layout different for primary and
> secondary (probably not-so-much DRBD question, but it kind of is related). By
> different I mean - it was showing the size of /dev/xvda correctly, but it was
> showing only 2 partitions on secondary box and 3 on primary

You didn't mention Linux distro but in general LVM2 is not cluster aware.
When you are on a SAN so, where both servers (in case of two) see the same PVs,
if you create a new LV or extend a pre-existing LV on one of them, the
other one is not able to detect the changes.
To accomplish this you have to use clvmd on Red Hat based systems
(found in package lvm2-cluster).
At the same time clvmd depends on Red Hat Cluster Suite (cman and
dependant packages).
This way if you add an LV on one node, you can immediately do an
lvdisplay for that on the other node.
Probably with drbd there is something similar involved.
I'm testing clvmd on top od drbd in primary/primary, where drbd is a
PV on top of which there is one VG with many LVs, so it is somewhat
the opposite in respect of your config. My aim is similar, but using
Qemu/KVM as the Hypervisor.
When I have figures of limits/features of my config we can share....

see also docs:


More information about the drbd-user mailing list