10 juillet 2015 08:46 "Digimer" <[email protected]> a écrit:
> 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. > OK Thank you for the explanation between the 2 concepts. >> - 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. > Actually the problem is that this test (and very low-cost) platform is hosted elsewhere. I just found that there is a REST API to maybe reboot the nodes. But for that Ill have to write a fence_agent. I'm not familiar with python or perl, I'm just experienced in bash programming. Is it possible to launch a simple shell script (making a curl) as fence agent ? >> - 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. > If this demo cluster works I ll be able to have owned machines with idrac/ipmi so it will be easier. Setting up the demo cluster is harder that the production one :) >> - 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 _______________________________________________ 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
