[ClusterLabs Developers] How to implement fencing agent with no associated hardware device with Pacemaker?

Reid Wahl nwahl at redhat.com
Wed Jul 29 23:42:25 EDT 2020

I didn't see the phrase "how to develop" until after I sent the previous
message. What is the reason for needing to develop a custom fencing agent?
An already-built one might save you some work.

Basically, you need some reliable method to cut off an unhealthy node's
access to shared storage, without depending on that node being responsive.
So for example, anything that involves logging into the failed node is

On Wed, Jul 29, 2020 at 8:40 PM Reid Wahl <nwahl at redhat.com> wrote:

> If you have a hardware **watchdog timer**, then sbd is a good option. With
> shared storage, you can also implement fence_sbd.
> KVM virtual machines also offer an emulated hardware watchdog. I'm not
> sure whether that would fit your criteria or not -- it depends on whether
> you're only excluding a management interface like an iLO/IMM, or whether
> you're also excluding a watchdog timer.
> If you can't use sbd or conventional power fencing (e.g., fence_ipmilan),
> then you may be able to use fence_scsi or fence_mpath since you have shared
> storage.
> What hardware or virtualization platform are you running on, and is there
> a particular reason you don't want to associate fencing with a hardware
> device?
> On Wed, Jul 29, 2020 at 8:34 PM Philippe M Stedman <pmstedma at us.ibm.com>
> wrote:
>> Hi ClusterLabs developers,
>> I am looking into how to develop a fencing agent for Pacemaker that is
>> not associated to any underlying hardware device. In our case we have two
>> servers (we will expand to more in the future) which have access to shared
>> storage. When one of the two nodes fails, we expect the surviving node to
>> invoke our user-defined fencing agent and run a series of commands which
>> will "expel" the lost host from accessing shared storage.
>> Do you have any advice on how to go about implementing such a solution?
>> All the examples I can find online revolve around using some sort of
>> underlying hardware device to implement fencing.
>> Help is greatly appreciated.
>> Thanks,
>> *Phil Stedman*
>> Db2 High Availability Development and Support
>> Email: pmstedma at us.ibm.com
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> --
> Regards,
> Reid Wahl, RHCA
> Software Maintenance Engineer, Red Hat
> CEE - Platform Support Delivery - ClusterHA


Reid Wahl, RHCA
Software Maintenance Engineer, Red Hat
CEE - Platform Support Delivery - ClusterHA
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