I am re-purposing an old cluster that used to run RHEL4 and IBM's GPFS. The nodes are all HP NetServer LP1000r with 2GB RAM, and dual 1.4GHz PIII's with an additional 1Gbps Intel NIC, and a local 73GB 10k RPM SCSI disk. I have 48 of these nodes (and a couple spare). As the GPFS and RedHat licenses have been transferred to new machines, it is my intention to rebuild the nodes using CentOS 5 and use GFS. I have a couple TB of iSCSI storage to go with it. This is a low budget project and I need a fencing device. The nodes all support something called "Alert on Lan v2", which seems to have been a fore runner of IPMI. I have a separate "management" network, and have turned AOL on in the BIOS on each node. Googling turned up no documentation on how Alert on Lan works so some time later with Wireshark and the windows client I have some C code that sends magic packets of death to either power off, reset, or power cycle (off wait 15 seconds then on) the nodes. Testing shows that it is robust in that it works on a node that has kernel panicked and is otherwise totally hung. It is also fast, once magic packet of death received the node is off instantly. All that seems to be required on the client side is for the management NIC to be up and configured with an IP address. This is contrary to the suggestion that client software is need according to the rather sketchy HP documentation. All good so far. However I am not sure what the requirements of a fencing agent are. Can I rename my program fence_aol2 fiddle with cluster.conf and it will work? Does the fencing agent have to return specific exit codes? Should the fencing agent do something to test the magic packet of death worked or is simply sending it enough? Does the fencing agent need to be able to turn nodes on (I could use Wake On Lan for this) as well as off? Finally once I have a working and debugged AOL2 fencing agent, how does one go about submitting for inclusion in cluster suite. Alternatively if this is not wanted (Alert on Lan is a historical protocol and superseded by IPMI) what is the best way of pointing other users to it's existance? JAB. -- Jonathan A. Buzzard Tel: +441382-386998 Storage Administrator, College of Life Sciences University of Dundee, DD1 5EH -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
