[DRBD-user] lvm+drbd+xen problem

Gabriele kalus gabriele.kalus at fysik.lu.se
Thu Jun 12 11:25:49 CEST 2008

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

I don’t know if this is a drbd or a xen issue so I will post this on 
both lists.

I have 2 HP Proliant servers with SLES10 SP2 installed. There are 8 
disks on the system, 2 of the disks are in a hardware raid1 and the rest 
is raid5, also hardware. The servers have several network cards; one is 
exclusively for drbd replication. I use the drbd 0.7.22-42 that ships 
with SLES10 and kernel

The Xen host is installed on a non-lvm2 partition of 20 GB on the raid1. 
The rest of the raid1 are a volume group called system. I have several 
logical volumes on the volume group system, called mail-root, mail-swap, 
webmail-root, webmail-swap, etc. The *-root lvs are to be the drbd 
devices where the domUs systems are going to be installed. The *-swap 
are just for swap which I don’t want to replicate.

I have tested the setup without the domUs running but with mounted drbd 
devices and pulled the network cable that manages the replication. 
Everything works as it should; both servers continue working and 
replication starts as soon as I connect the cable again.

I have tested to install the domUs on file systems on the drbd devices, 
i.e. with the drbd devices mounted and it also works as it should.

But when I install the domUs on physical devices /dev/drbdx for the 
domUs and pull the network cable between the replicating nics the Xen 
host with the domUs running hangs. Only a cold boot gets it started 
again. The replication works as it should as long as the cable is there 
or as long as both servers are up, everything gets replicated through 
the dedicated nic. But if I reboot the passive server the active server 
hangs, i.e. the same situation as when I pull the network cable. I have 
all the domUs on one of the servers, the other server is just passive.

I haven't installed heart beat to avoid adding complexity to the situation.

Can somebody help me figure out why it I can’t get it to work when the 
domUs are installed on physical devices?



Gabriele Kalus
Lund University, Physics Department

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