[Linux-cluster] Quorum disk over RAID software device

[Rafael Micó Miranda]

Hi Jacov

El mar, 15-12-2009 a las 17:26 +0100, Jakov Sosic escribió:
> On Tue, 2009-12-15 at 15:31 +0100, Andreas Pfaffeneder wrote:
> 
> > 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.
> 
> So you have to create mdraid on every node of the cluster? But, is that
> legitimate way of doing things - because mdraid isn't cluster aware?
> It's like having a LVM without using clustered volumes... It's ok as
> long as you don't change metadata...
> 
> What about mdraid?
> 
> 
> 

As I see, in this situation of the usage of the shared storage volume as
a Qdisk there is no problem of the system being "not cluster aware". I
mean: a usual qdisk is a LUN with a "clustered" filesystem, to say it in
some way, in which all the cluster nodes can write an read at the same
time.

If you don't plan to change the LVM metadata of the qdisk (I don't) I
think this will be feasible. The same should happen with the MDADM
variant.

Today I configured a not-clustered volume group and then I built a
mirrored logical volume over it and configured it as a Qdisk. Then I
started CMAN and it worked OK using the LVM-mirror qdisk. 

Tomorrow (I hope) I'll do some tests to see what happens if only one of
the nodes loses one of the LUNs which build the LVM-mirror volume, and
what happens when the LUN is back.

Thanks for your interest. Cheers,

Rafael

-- 
Rafael Micó Miranda