[ClusterLabs] I question whether STONITH is working.

durwin at mgtsciences.com durwin at mgtsciences.com
Thu Feb 16 13:14:59 EST 2017 

Klaus Wenninger <kwenning at redhat.com> wrote on 02/16/2017 10:43:19 AM:

> From: Klaus Wenninger <kwenning at redhat.com>
> To: durwin at mgtsciences.com, Cluster Labs - All topics related to 
> open-source clustering welcomed <users at clusterlabs.org>
> Cc: kgaillot at redhat.com
> Date: 02/16/2017 10:43 AM
> Subject: Re: [ClusterLabs] I question whether STONITH is working.
> 
> On 02/16/2017 05:42 PM, durwin at mgtsciences.com wrote:
> Klaus Wenninger <kwenning at redhat.com> wrote on 02/16/2017 03:27:07 AM:
> 
> > From: Klaus Wenninger <kwenning at redhat.com> 
> > To: kgaillot at redhat.com, Cluster Labs - All topics related to open-
> > source clustering welcomed <users at clusterlabs.org> 
> > Date: 02/16/2017 03:27 AM 
> > Subject: Re: [ClusterLabs] I question whether STONITH is working. 
> > 
> > On 02/15/2017 10:30 PM, Ken Gaillot wrote:
> > > On 02/15/2017 12:17 PM, durwin at mgtsciences.com wrote:
> > >> I have 2 Fedora VMs (node1, and node2) running on a Windows 10 
machine
> > >> using Virtualbox.
> > >>
> > >> I began with this.
> > >> http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/
> > Clusters_from_Scratch/
> > >>
> > >>
> > >> When it came to fencing, I refered to this.
> > >> http://www.linux-ha.org/wiki/SBD_Fencing
> > >>
> > >> To the file /etc/sysconfig/sbd I added these lines.
> > >> SBD_OPTS="-W"
> > >> SBD_DEVICE="/dev/sdb1"
> > >> I added 'modprobe softdog' to rc.local
> > >>
> > >> After getting sbd working, I resumed with Clusters from Scratch, 
chapter
> > >> 8.3.
> > >> I executed these commands *only* one node1.  Am I suppose to run 
any of
> > >> these commands on other nodes? 'Clusters from Scratch' does not 
specify.
> > > Configuration commands only need to be run once. The cluster
> > > synchronizes all changes across the cluster.
> > >
> > >> pcs cluster cib stonith_cfg
> > >> pcs -f stonith_cfg stonith create sbd-fence fence_sbd
> > >> devices="/dev/sdb1" port="node2"
> > > The above command creates a fence device configured to kill node2 -- 
but
> > > it doesn't tell the cluster which nodes the device can be used to 
kill.
> > > Thus, even if you try to fence node1, it will use this device, and 
node2
> > > will be shot.
> > >
> > > The pcmk_host_list parameter specifies which nodes the device can 
kill.
> > > If not specified, the device will be used to kill any node. So, just 
add
> > > pcmk_host_list=node2 here.
> > >
> > > You'll need to configure a separate device to fence node1.
> > >
> > > I haven't used fence_sbd, so I don't know if there's a way to 
configure
> > > it as one device that can kill both nodes.
> > 
> > fence_sbd should return a proper dynamic-list.
> > So without ports and host-list it should just work fine.
> > Not even a host-map should be needed. Or actually it is not
> > supported because if sbd is using different node-naming than
> > pacemaker, pacemaker-watcher within sbd is gonna fail. 
> 
> I am not clear on what you are conveying.  On the command 
> 'pcs -f stonith_cfg stonith create' I do not need the port= option?
> 
> e.g. 'pcs stonith create FenceSBD fence_sbd devices="/dev/vdb"'
> should do the whole trick.

Thank you.  Since I already executed this command, executing it again
without device= says device already exists.  What is correct way to
remove current device so I can create it again without device=?

Durwin

> 
> 
> Ken stated I need an sbd device for each node in the cluster 
> (needing fencing). 
> I assume each node is a possible failure and would need fencing. 
> So what *is* a slot?  SBD device allocates 255 slots in each device. 
> These slots are not to keep track of the nodes?
> 
> There is a slot for each node - and if the sbd-instance doesn't find
> one matching
> its own name it creates one (paints one of the 255 that is unused 
> with its own name).
> The slots are used to send messages to the sbd-instances on the nodes.

> 
> 
> Regarding fence_sbd returning dynamic-list.  The command 
> 'sbd -d /dev/sdb1 list' returns every node in the cluster. 
> Is this the list you are referring to?
> 
> Yes and no. fence_sbd - fence-agent is using the same command to create 
that
> list when it is asked by pacemaker which nodes it is able to fence.
> So you don't have to hardcode that, although you can of course using a
> host-map if you don't want sbd-fencing to be used for certain nodes 
because
> you might have a better fencing device (can be solved using 
fencing-levels
> as well).

> 
> 
> Thank you, 
> 
> Durwin 
> 
> > 
> > >
> > >> pcs -f stonith_cfg property set stonith-enabled=true
> > >> pcs cluster cib-push stonith_cfg
> > >>
> > >> I then tried this command from node1.
> > >> stonith_admin --reboot node2
> > >>
> > >> Node2 did not reboot or even shutdown. the command 'sbd -d 
/dev/sdb1
> > >> list' showed node2 as off, but I was still logged into it (cluster
> > >> status on node2 showed not running).
> > >>
> > >> I rebooted and ran this command on node 2 and started cluster.
> > >> sbd -d /dev/sdb1 message node2 clear
> > >>
> > >> If I ran this command on node2, node2 rebooted.
> > >> stonith_admin --reboot node1
> > >>
> > >> What have I missed or done wrong?
> > >>
> > >>
> > >> Thank you,
> > >>
> > >> Durwin F. De La Rue
> > >> Management Sciences, Inc.
> > >> 6022 Constitution Ave. NE
> > >> Albuquerque, NM  87110
> > >> Phone (505) 255-8611
> > >
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