[Pacemaker] Node level fencing advice

Matthew O'Connor matt at ecsorl.com
Wed Aug 21 13:46:34 EDT 2013


I have used a small variety of fencing on my very small clusters.  My
opinions here are all my own. ;-) Here's what I've had experience with:

  * USB-capable APC Back-UPS with NUT (
http://www.networkupstools.org/).  It works and has served me well for
two, three, and four node clusters.  With two-node clusters I
cross-connect the nodes to each other's UPSs, obviating the need for a
third system to act as the NUT server.  (I detailed my experiences with
setting up UPS+NUT-based stonith on my blog:
I would have larger clusters talk to a central (non-cluster) NUT server;
occasionally an interruption in communication would cause the stonith
resource to fail and thus make stonith impossible until the failure was
cleared, but luckily this seemed to be rare (and non-existent in the
cross-connected case).

  * APC PDU ( Model AP7900), via SNMP.  These work very well for me,
though I've found you have to tweak the timing parameters in the stonith
agent to get it to work correctly (i.e. to shut down the outlet for
sufficient time, and not just a brief off-on operation).  I like them
very much; they provide per-outlet control and are not too expensive. 
Its web interface is also very handy for remote-controlling both cluster
and non-cluster systems.

  * IPMI on Supermicro-based motherboards.  I've heard good things, and
not-so-good things.  In my environment, issues with keeping connected
with IPMI was the reason I moved away from using it; the IPMI would
eventually just stop responding to commands.  I suspect it's an issue
with the IPMI itself, something unresolved that only Supermicro can
fix.  As with any stonith, test thoroughly.  Some folks do a two-step
stonith: IPMI, then power, just to make doubly-sure. 

Hope this helps!

On 08/16/2013 06:13 PM, Nick Khamis wrote:
> Hello Everyone,
> We are in the market for a new UPS. And would like to know some of
> your experiences given the different means of stonith (ie, ups, pdu,
> blade hardware). The UPS unit we are looking at
> is:http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SYA4K8RMP&total_watts=500.
> But before all that would like to know if RSA/iLO/DRAC is the
> preferred way of implementing it?
> One thing to think of is that with a UPS stonith, there is less worry
> of drivers, kernel modules etc...? As for PDU level stontih, can we
> really expect anything more from our PDU other than distribution?
> Have more questions but for the sake of brevity...
> Kind Regards,
> Nick.
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Thank you!
  Matthew O'Connor
  (GPG Key ID: 55F981C4)

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