[DRBD-user] Detection of Logical Volume on nested LVM

Lars Ellenberg lars.ellenberg at linbit.com
Tue Mar 9 11:22:52 CET 2010

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, Mar 09, 2010 at 10:59:54AM +0100, Olivier LAMBERT wrote:
> I've got your point. I know my first message is long and maybe
> complicated. It seems you "jump" some lines. It's not "nested" LVM as
> described in the doc (because I RTFM before try to ask help).
> My problem is not located on DRBD hosts. I've run some test, and I can
> really simplify the example. Please, read this, I think it's clear now
> :
> Let's say I export a simple physical volume with DRBD. So, NO LVM in
> DRBD, just replicate "/dev/sdb" for example, and export it
> (/dev/drbd0) on each DRBD host with iSCSI.
> So, on ALL my clients (connected iSCSI), I saw with "fdisk -l" :
> Disk /dev/sdb: 2998.8 GB, 2998869356544 bytes
> So, my CLIENT1 connected to DRBD1, decide to create a volume group and
> a logical volume.
> Despite all my efforts (vgscan, pvscan, lvscan), CLIENT2 connected to
> replicated DRBD2, cannot see anything ! No VG, no LV ! Nothing !
> But, if I decide to do that on DRBD2 :
> drbdadm disconnect ressource && drbdadm connect ressource
> Just after THIS, I can see all the stuff I've created on CLIENT1.
> So, it's NOT a question of LVM on DRBD, because in this case, I don't
> use it anymore. I can undestand if LVM data's on client are not
> replicated on each DRBD hosts, but WHY it works if I
> disconnect/reconnect these two ? It doesn't have any sense to me....

Does the keyword "cache coherence" help?

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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