You may prefer to use the clusterlabs mailing list. This list is being phased out.
On 16/10/15 05:20 AM, Shilu wrote: > When master is down, can the time of switching backup to master be > shorter than a second? Not safely, no. In HA, if a node is declared dead, it needs to be fenced/stonith'ed before its services are recovered. Not doing this can lead to a split-brain. The process of fencing a node takes time; Exactly how much depends on the device or method you are using. IPMI fencing, one of the most common types, takes a few seconds. Also, if you shorten the time it takes to declare a node dead, you increase the chance of having a node declared dead when it's not. > The following is the switching time about keepalived. Can Heartbeat be > more excellent? Heartbeat is long deprecated. The modern stack is Corosync + Pacemaker. Here is why: https://alteeve.ca/w/History_of_HA_Clustering > No, it can't be shorter than 1 second. This is a VRRP protocol > limitation. Most enterprise-class VRRP implementation are using a BFD > protocol to achieve sub-second fault detection time. I've created > proof-of-concept BFD subsystem for keepalived some time ago - > https://github.com/ivoronin/keepalived/tree/bfd . Unfortunately it is > not well tested and not suitable for production use. I've never been a big fan of keepalived because it does not fence. It assumes that the peer is dead, and when people test it, they kill the node so in those cases it was a safe assumption. In the real world though, losing access to a node is no guarantee that it is actually failed. So people think they're safe, until they're not. -- 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
