[DRBD-user] DRBD 8.0 primary / primary and LVM

Maxim Doucet maxim at alamaison.fr
Fri Jun 29 12:56:24 CEST 2007

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

Reqding this (source
http://lists.linbit.com/pipermail/drbd-user/2007-June/007062.html) :

H.D. a écrit :
> On 28.06.2007 15:03, prashant wrote:
>> Does DRBD8.0 can mount secondary as read-write.
> It allows two primaries, yes.
>> If yes - is there additional steps to do before mounting a partition.
> Besides the two primaries option in the config, no.
> But be sure to use a cluster file system, such as OCFS or GFS.

I thought about this :

What if the DRBD resource is used as a LVM's Physical Volume (PV) with a
Volume Group (VG) on top ?

In my case, I am studying a solution for XEN's virtual machines storage.
I'd like to have several Logical Volumes (LV) into the Volume Group
(VG), one per virtual machine.

3 points here :
(1) Let's take 2 virtual machines : VM1 and VM2. I want VM1 to run on
server A and VM2 on server B. Each virtual machine have its own Logical
(2) I'd like to use drbd 8.0 in primary/primary configuration so I can
run only one drbd resource for the VG which stores the 2 Logical Volumes
(3) because of (1), the Logical Volumes are not concurrently accessed :
one Logical Volume is only mounted in one node and will be replicated 
to the other

So : Logical Volumes are not mounted on both nodes but the Physical
Volume (PV)/Volume Group (VG) under the Logical Volumes is used on both
nodes, at the same time.

Question : does PV/VG can be accessed concurrently or do I have to use
RedHat's Cluster LVM (clvm) ?

Maxim Doucet
sys admin @ la maison

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