Hi, On Wed, May 05, 2010 at 08:06:39AM -0600, Greg Woods wrote: > On Wed, 2010-05-05 at 13:29 +0200, Dejan Muhamedagic wrote: > > > If these servers have a lights-out device and the power > > distribution is fairly reliable, that could be an alternative for > > fencing. > > They do have an IPMI device and it does work. I am trying to insulate > against a failure of the NIC or cable by having a second stonith device. > > The cluster I have now is primarily for testing, but eventually we will > be implementing critical services (e.g. DNS, e-mail, DHCP, and > authentication) in virtual machines running on a cluster like this one, > so part of the testing process is to learn what can and can't be done > and where the potential gotchas are. I have discovered that if I > simulate a cable failure by removing it, bad things happen because > stonith cannot succeed. I would not want my DNS system to be vulnerable > to a single cable failing, so I am looking for ways to guard against it.
rackpdu also works over the network. The lights-out device has its own network interface. Presumably both should be connected to some management network. Where's the difference? > A complete power outage on one of the nodes also results in bad things > when using IPMI. Again stonith cannot succeed and so the remaining > server will not take over the resources. Yes, these are dual power > supply servers so it is unlikely that something would happen that causes > only one of the servers to completely lose power other than human error > (possibly a motherboard failure as well?) That's an interesting question. Perhaps the server vendor can tell. > but I am still looking to > determine if there is a way to guard against this. Right now I have a > "meatware" stonith device set up so that I can at least log in remotely > and manually force the remaining server to take over, but I am looking > for something more automatic. It would be nice to avoid those 3AM phone > calls )-: You can have more than one stonith resource and they'll be tried in a round-robin fashion until one succeeds. > I may take a shot at modifying the external/rackpdu stonith plugin at > some point. We can't be the only ones in the world using dual power > supply servers. I'll probably start by unplugging one of the power > supplies on each server and making sure I understand how to use the > plugin in single-outlet mode, then try doing the modifications to > support dual outlets. The plugin picks the outlet in one of the two ways: - from the device itself, provided that the outlet name matches the node name - from the external file which specifies the mapping I can help with modifying the plugin if you'll do the testing. Thanks, Dejan > --Greg > > > _______________________________________________ > Linux-HA mailing list > [email protected] > http://lists.linux-ha.org/mailman/listinfo/linux-ha > See also: http://linux-ha.org/ReportingProblems _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
