On 01/27/2012 03:20 PM, yvette hirth wrote: > Digimer wrote: > >> You can crash the machine with this; >> >> echo c > /proc/sysrq-trigger > > will > > ifconfig ethx down (where "x" = heartbeat ethernet interface numbah) > > do the same thing? > > yvette Nope. The scenario is caused by both nodes being alive, but losing the ability to talk to one another on the storage channel. Whether it is because a given cable is unplugged or a bad firewall rule, the result is the same; Both nodes see a failure at the same time and call their fence handlers at the same time. The one with the sleep will delay, and thus, always lose (and be the fence victim). The idea behind sending "c" to sysre-trigger is that it hangs the kernel entirely. The hung node will no trigger it's fence, or do anything else for that matter. Meanwhile, the node with the sleep will detect the fault, call the agent, sleep for a few seconds, then proceed to fence the hung node. This more accurately simulates an actual fault in the primary node and confirms that the sleep'ed node will in fact fence successfully. -- Digimer E-Mail: digimer@xxxxxxxxxxx Papers and Projects: https://alteeve.com -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
