[Linux-cluster] Quorum disk over RAID software device

Rafael Micó Miranda rmicmirregs at gmail.com
Tue Dec 15 19:01:00 UTC 2009

Hi Andreas

El mar, 15-12-2009 a las 15:31 +0100, Andreas Pfaffeneder escribió:
> Hi Rafael,
> Am 14.12.2009 23:15, schrieb Rafael Micó Miranda:
> > Hi all,
> >
> > I was wondering if there is a way to achieve a "quorum disk over a RAID
> > software device" working CMAN cluster.
> >
> >    
> in a similar situation I am using a raid-1 device (built with mdadm 
> prior to the startup of cman/rgmanager) which consists of two luns, one 
> in each location. This works pretty well as quorum-device.
> Andreas
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-cluster

Today I tried this approach, but I have no previous experience with
MDADM. The problem I found was, how do you manage multipath on the
different LUNs without device-mapper-multipath?

As I see in the system logs the MD driver loads before
device-mapper-multipath is working, and it uses the devices (/dev/sdX)
to assemble the RAID devices (/dev/mdX) before the devices are available
through device-mapper-multipath (/dev/mapper/quorumdiskX) at system boot
time. This even makes the device-mapper-multipath devices not getting
built when multipathd starts after that. Does this happen to you? 

So, I tried to configure a multipath device with MDADM and after that
use the built devices to assemble a RAID1 MD device. This was the config
in mdadm.conf I used:

DEVICE /dev/sd*

ARRAY /dev/md1 metadata=1.1 level=multipath num-devices=2
ARRAY /dev/md2 metadata=1.1 level=multipath num-devices=2
ARRAY /dev/md3 metadata=1.2 level=raid1 num-devices=2 name=quorum

Devices where all with the "Linux raid auto" partition mark. When I
built the MDs first everything seemed to work, but after a system boot
the /dev/md3 device was not built, so the quorum disk would not be
available for CMAN.

How do you implement this with MDADM?

Thanks in advance,


Rafael Micó Miranda

More information about the Linux-cluster mailing list