>>> Digimer <[email protected]> schrieb am 18.04.2017 um 19:08 in Nachricht <[email protected]>: > On 18/04/17 11:07 AM, Lentes, Bernd wrote: >> Hi, >> >> i'm currently establishing a two node cluster. Each node is a HP server with > an ILO card. >> I can fence both of them, it's working fine. >> But what is if the ILO does not work correctly ? Then fencing is not > possible. > > Correct. If you only have iLO fencing, then the cluster would hang > (failed fencing is *not* an indication of node death). > >> I also have a switched PDU from APC. Each server has two power supplies. > Currently one is connected to the normal power equipment, the other to the > UPS. >> As a sort of redundancy, if the UPS does not work properly. > > That's a fine setup. > >> When i'd like to use the switched PDU as a fencing device i will loose the
> redundancy of two independent power sources, because then i have to connect > both power supplies together to the UPS. >> I wouldn't like to do that. > > Not if you have two switched PDUs. This is what we do in our Anvil! > systems... One PDU feeds the first PSU in each node and the second PDU > feeds the second PSUs. Ideally both PDUs are fed by UPSes, but that's > not as important. One PDU on a UPS and one PDU directly from mains will > work. > >> How important would you consider to have two independent fencing device for > each node ? I'd can't by another PDU, currently we are very poor. > > Depends entirely on your tolerance for interruption. *I* answer that > with "extremely important". However, most clusters out there have only > IPMI-based fencing, so they would obviously say "not so important". > >> Is there another way to create a second fencing device, independent from the > ILO card ? >> >> Thanks. > > Sure, SBD would work. I've never seen IPMI not have a watchdog timer > (and iLO is IPMI++), as one example. It's slow, and needs shared > storage, but a small box somewhere running a small tgtd or iscsid should > do the trick (note that I have never used SBD myself...). Slow is relative: If it takes 3 seconds from issuing the reset command until the node is dead, it's fast enough for most cases. Even a switched PDU has some delays: The command has to be processed, the relay may "stick" a short moment, the power supply's capacitors have to discharge (if you have two power supplys, both need to)... And iLOs don't really like to be powered off. Ulrich > > -- > Digimer > Papers and Projects: https://alteeve.com/w/ > "I am, somehow, less interested in the weight and convolutions of > Einstein’s brain than in the near certainty that people of equal talent > have lived and died in cotton fields and sweatshops." - Stephen Jay Gould > > _______________________________________________ > Users mailing list: [email protected] > http://lists.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://lists.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
