Hi Alex, > -----Ursprüngliche Nachricht----- > Von: "Alex Strachan" <[EMAIL PROTECTED]> > Gesendet: 30.10.08 13:37:53 > An: "'General Linux-HA mailing list'" <[email protected]> > Betreff: RE: [Linux-HA] Stonith, 2 node cluster - on loss > ofpowertoprimarynode; failure to secondary didn't happen.
> The first test my boss likes to apply to a HA setup is to remove the power > cords from the back of the running primary server. The question is: What does he expect? If he likes stonithing going on then he has to spend money for an external stonith device. > > By having a stonith device (IBM RSA) running from the same power as the host > the failover no longer happens. :-( This is a design flaw. RSA-Boards are not made for stonithing primarely. ;-) But you get a stonith device for many scenarios without additional costs. > We could power the RSA independently - maybe there is a battery backed power > pack available for it - who know. There was an older RSA-I-Board which gets its power by a simple plugin-power-supply as you know from e.g. shavers. IMHO it's better to have the hopefully redundant power supply of the server. > Otherwise my boss will pull all three > power cables at the same time - two for the server plus one for the RSA! And that is exactly the point! Ask: What failure scenario do I want to secure with how much money? In your case you have to secure the following scenario: "Boss is running around pulling power cables." Buy a lock for the computer center. :-) EVERY stonith device HA has to communicate to electronically needs power. If there is no power no reliable stonith operation. Even if it runs by batteries your boss would pull out the batteries. IMHO: Yes think about all failure scenarios. Weight them with the probability of the occurence. Measure how costly it is to protect this failure and how costly it is not to protect it. And then decide! Or better your boss, because as soon as it gets expensive many failure scenarios are suddenly acceptable... :-)) By the way: HA = High Availability and not AA = Absolute Availability :-) Best regards Andreas Mock _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
