[Cluster-devel] unfencing

[Ryan O'Hara]

On Fri, Feb 20, 2009 at 03:44:32PM -0600, David Teigland wrote:

> [Note: we've talked about fence_scsi getting a device list from
>  /etc/cluster/fence_scsi.conf instead of from clvm.  It would require
>  more user configuration, but would create fewer problems and should
>  be more robust.]

Agreed. The "discovery" concept in scsi_reserve/fence_scsi limits its
use to clvm volumes. How to configure devices for use with scsi
reservations is a problem that will need to be addressed.

> fence_node_undo("bar") would:
> - fork fence_brocade
> - pass arg string: undo port="4" agent="fence_brocade" ipaddr="1.1.1.1"
> - fork fence_brocade
> - pass arg string: undo port="6" agent="fence_brocade" ipaddr="2.2.2.2"
> - ignore device "apc" because it's not found under <unfencedevices>

What happens if unfencing fails? Is it safe to say that a node that
fails to unfence itself will be prohibited from joining the fence
domain? This is important for fence_scsi, since unfencing is
equivalient to re-registering with the scsi devices. Failure to
unfence (ie. register) precludes that node from being able to fence
other nodes. I'm not sure if other fencing methods have this type of
requirement.