[Linux-cluster] fencing device

Jakub Suchy jakub.suchy at enlogit.cz
Wed Dec 10 08:24:05 UTC 2008


> Does this mean that I can use this IPMI fencing to fence the cluseter
> nodes? Does this provide functionality smiliar to as using apc or hp
> power switchs?

HP iLO is supported as a fencing device. If you are serious, you should
still consider power fencing (don't forget, that fencing can be a SPOF,
you need two fencing devices).

iLO/IPMI fencing has some serious consequences:
- It's not a shared device. It MUST be on the same network path as
- It's not a shared device. You must really think about race conditions
  and nodes fencing each other, especially in 2 nodes cluster.
- Server out of power = iLO out of power. After a recent update of cman
  in RHEL5.2, rgmanager now waits for fencing to complete before
  starting any services. If one node is offline (away for repair, etc.)
  then it's fencing will never complete and you are stuck.

We succesfully use two APC 7920 power switches crossed together as
fencing devices, they are 8 ports, 1U rack mountable. Don't know if they
are available in US, I live in Europe...


Jakub Suchý <jakub.suchy at enlogit.cz>
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