[Linux-cluster] qdisk and multipathing problems

[Riaan van Niekerk]

I am trying to get qdisk going in a 2-node RHCS 4.4 cluster with EMC 
PowerPath

I was able to format the device:
mkqdisk -c /dev/emcpowera1 -l quorum_disk_1

this command shows multiple copies (4 paths, native devices, and one EMC 
pseudo device)

[jabbah:~]# mkqdisk -L
mkqdisk v0.5
/dev/sdc1:
         Magic:   eb7a62c2
         Label:   quorum_disk_1
         Created: Mon Oct 30 16:15:57 2006
         Host:    sargas.telkomsa.net

/dev/sdd1:
         Magic:   eb7a62c2
         Label:   quorum_disk_1
         Created: Mon Oct 30 16:15:57 2006
         Host:    sargas.telkomsa.net

/dev/sdg1:
         Magic:   eb7a62c2
         Label:   quorum_disk_1
         Created: Mon Oct 30 16:15:57 2006
         Host:    sargas.telkomsa.net

/dev/sdh1:
         Magic:   eb7a62c2
         Label:   quorum_disk_1
         Created: Mon Oct 30 16:15:57 2006
         Host:    sargas.telkomsa.net

/dev/emcpowera1:
         Magic:   eb7a62c2
         Label:   quorum_disk_1
         Created: Mon Oct 30 16:15:57 2006
         Host:    sargas.telkomsa.net


Here is my stanza from cluster.conf

<quorumd interval="1" tko="10" votes="2" device="/dev/emcpowera1" 
label="quorum_disk_1">
  <heuristic program="ping 192.168.222.254 -c1 -t1" score="2" interval="2"/>
</quorumd>

I tell it to use /dev/emcpowera1 but it insists on using the first path, 
  /dev/sdc1

[jabbah:~]# cat /proc/cluster/nodes
Node  Votes Exp Sts  Name
    0    2    0   M   /dev/sdc1
    1    1    2   M   jabbah
    2    1    2   M   sargas

Is there any way to blacklist /dev/sd* devices from being scanned 
(similar to what is done for LVM)? or force qdisk to use /dev/emcpowera1?

using the native device is bad for obvious reasons (if you lose the 
path, you lose the node or even the whole quorum disk, depending on 
where the path failure is)

qdisk seems somewhat unreliable with my setup, with intermittent 
messages like this:

Oct 31 10:22:57 sargas qdiskd[18712]: <crit> Critical Error: More than 
one master found!
Oct 31 10:22:58 sargas qdiskd[11964]: <crit> A master exists, but it's 
not me?!

Also, "mkqdisk -f" does not "Find the cluster quorum disk with the given 
label" but instead just displays the version number

[jabbah:~]# mkqdisk -f  quorum_disk_1
mkqdisk v0.5

is this a bug? I logged it as 
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=213218

greetings
Riaan
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