On 09/07/15 11:37 PM, Nicolas S. wrote: > Hello, > > I'm working on a 3 node cluster project. > I didnt want to go to 2 node cluster , I'd rather3 nodes for the > ressources, and to have a quorum. My 3 machines are identical. > > Each machine exports a disk to the cluster via iscsi (it's to simulate a > SAN on my test platform). > For the moment all is running : dlm + clvm (+ cmirror) + gfs2 > > I now want to add the fencing to my cluster (for the moment it's > disabled in the cluster config). My problem is to choose the right > fencing/stonith. > > My questions : > > - As I have a quorum , do I need fencing ?
Yes. Quorum is a tool useful when the cluster nodes are behaving predictably. Fencing is a tool for when a node has entered an unknown state. They solve different problems. > - I can't use an ipmi/drac or so fencing agent, my cluster is on a very > low-cost test platform it hasn't remote reboot/poweroff access. Then you will need to use an external device, like a switched PDU. > - Maybe I could use the fence_scsi, but how to use it on 3 nodes ? > Where should I place the fencing disk ? If the node exporting the disk > fails, there is no more fencing. This would disconnect the failed VM from the shared storage, but leave it otherwise alone. Personally, I don't like this because though the storage is safe, it's possible for the node to still cause trouble. I much prefer, and always recommend, power fencing. > - Any other advice will be helpful :) APC-brand AP7900 switched PDUs are excellent and fast fence devices. They can often be found used for under $200usd. If this is still too much, and if this is a learning platform, something I did when I first learned was to create an arduino-based fence device (http://nodeassassin.org). > Regards, > > Nicolas. -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education? _______________________________________________ Users mailing list: [email protected] http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org
