On 08/02/2012 06:28 PM, Yount, William D wrote: > So I have been giving some thought to my fencing agent, as it seems a proper > fencing solution is integral to any cluster. I only have access to basic > Optiplex 990 and 960 desktops which is what I have built my cloud out of. I > have been using the fence_pcmk agent but that doesn't seem to be a great > solution. It can send shutdown and reboot commands to other nodes, but the > nodes usually get hung-up in their shutdown scripts waiting for NFS shares to > unmount or for VMs to turn off. > > One agent that seems to come up a lot is OpenIPMI. I have done some reading > on it and I can't quite get an understanding of if this is a software > solution that doesn't need any hardware implementation such as a special IPMI > management board. Can anyone let me know if I need hardware that specifically > supports IPMI? > > > > William
To clarify; A fence agent is designed to talk to a specific target device. So fence_ipmilan only works if the target machine has an IPMI BMC (baseboard management controller). Now I don't know Dell hardware, but most desktop-class equipment does not have IPMI on it. These IPMI BMCs are almost like little mini computers; They pull their power from the same system, they can read the sensors of the host, etc, but they are independent. These IPMI BMC are not generic devices you can add to a machine, they have to be designed for the host. So if you don't have IPMI, you're likely not going to add one. You are right; fencing is critical. Fence agents that rely on the target responding properly are fundamentally flawed and unreliable. The whole idea behind fencing is to put a node in an unknown state into a known state. If you don't know a node's state, there is a very good chance you won't be able to talk to it, or even if you can, as you've seen, it isn't operating properly anymore. The best option at this point would be to use a switched PDU, like the APC AP7900 (or similar, higher port-count version). These are effectively network-connected power bars with individual outlet control. You have to choose the maker carefully, as not all switched PDUs have agents (APC, Eaton and a couple others do, I think). This is your best bet to add fencing to your desktop machines. Cheers -- Digimer Papers and Projects: https://alteeve.com _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
