[Pacemaker] cman + corosync + pacemaker + fence_scsi

[Andreas Mock]

Hi Angel,

two hints from my side. As you're working with ubuntu
ask in this list which setup is or will be the best
concerning corosync + pacemaker. I'm pretty sure
(but I really don't know) that you'll get the advice
to drop cman.

When you use cman + pacemaker than stonithing works
as following. Use the pcmk-redirect in cman which
causes that cman delegates stonith commands to
pacemaker. In pacemaker you have to add the
stonith agents which use your hardware. You
have to enable stonithing in pacemaker with
stonith-enabled="true".

Another issue with stonithing. In a two node cluster
you have to configure the stonith agents in a
way that the remaining part (which ever it is,
mostly the faster one) is able to shoot the other
node even when cluster communication is lost.
When the stonith action is done over the same
wire as your cluster communication than stonithing
is meaningless.

Best regards
Andreas Mock


-----Ursprüngliche Nachricht-----
Von: Angel L. Mateo [mailto:amateo at um.es] 
Gesendet: Mittwoch, 24. April 2013 14:49
An: The Pacemaker cluster resource manager
Betreff: [Pacemaker] cman + corosync + pacemaker + fence_scsi

Hello,

	I'm trying to configure a 2 node cluster in ubuntu with cman +
corosync 
+ pacemaker (the use of cman is because it is recommended at pacemaker 
quickstart). In order to solve the split brain in the 2 node cluster I'm 
using qdisk. For fencing, I'm trying to use fence_scsi and in this point 
I'm having the problem. I have attached my cluster.conf.

xml <node id="/dev/block/8:33" type="normal" uname="/dev/block/8:33"/>
node myotis51
node myotis52
primitive cluster_ip ocf:heartbeat:IPaddr2 \
	params ip="155.54.211.167" \
	op monitor interval="30s"
property $id="cib-bootstrap-options" \
	dc-version="1.1.6-9971ebba4494012a93c03b40a2c58ec0eb60f50c" \
	cluster-infrastructure="cman" \
	stonith-enabled="false" \
	last-lrm-refresh="1366803979"

	At this moment I'm trying just with an IP resource, but at the end
I'll 
get LVM resources and dovecot server running in top of them.

	The problem I have is that whenever I interrupt network traffic
between 
my nodes (to check if quorum and fencing is working) the IP resource is 
started in both nodes of the cluster.

	So it seems that node fencing configure at cluster.conf is not
working 
for me. Then I have tried to configure as a stonith resource (since it 
is listed by sudo crm ra list stonith), so I have tried to include

primitive stonith_fence_scsi stonith:redhat/fence_scsi

	The problem I'm having with this is that I don't know how to
indicate 
params for the resource (I have tried params devices="...", params -d 
..., but they are not accepted) and with this (default) configuration I get:

pr 24 14:39:14 myotis51 lrmd: [6759]: debug: on_msg_perform_op: add an 
operation operation monitor[5] on stonith_fence_scsi for client 6763, 
its parameters: crm_feature_set=[3.0.5] CRM_meta_timeout=[20000]  to the 
operation list.
Apr 24 14:39:14 myotis51 lrmd: [6759]: info: rsc:stonith_fence_scsi 
probe[5] (pid 10434)
Apr 24 14:39:14 myotis51 lrmd: [10434]: ERROR: get_stonith_provider: No 
such device: redhat/fence_scsi
Apr 24 14:39:14 myotis51 lrm-stonith: [10434]: ERROR: execra: No such 
legacy stonith device: redhat/fence_scsi
Apr 24 14:39:14 myotis51 lrm-stonith: [10434]: debug: execra: 
stonith_fence_scsi_monitor returned -12
Apr 24 14:39:14 myotis51 lrmd: [6759]: WARN: Managed 
stonith_fence_scsi:monitor process 10434 exited with return code 7.
Apr 24 14:39:14 myotis51 lrmd: [6759]: info: operation monitor[5] on 
stonith_fence_scsi for client 6763: pid 10434 exited with return code 7
Apr 24 14:39:14 myotis51 crmd: [6763]: debug: create_operation_update: 
do_update_resource: Updating resouce stonith_fence_scsi after complete 
monitor op (interval=0)
Apr 24 14:39:14 myotis51 crmd: [6763]: info: process_lrm_event: LRM 
operation stonith_fence_scsi_monitor_0 (call=5, rc=7, cib-update=57, 
confirmed=true) not running

	I'm trying to use fence_scsi because I'm planning to use a shared 
storage (accesed via scsi fibre channel) and I don't want to use CLVM 
(because I need lvm snapshots, not supported by clvm), so I need a 
fencing device avoiding to concurrently use the same scsi devices in 
both nodes.

	Any idea on how to use fence_scsi? Or I could use any other 
fence/stonith device? Which one do you recommend?

-- 
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337