[ClusterLabs] I question whether STONITH is working.

Thu Feb 16 18:43:19 CET 2017

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.

>
>
> 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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