If a cluster splits into two (or more) groups of nodes that can no longer communicate with each other (aka. partitions), quorum is used to prevent resources from starting on more nodes than desired, which would risk data corruption.
A cluster has quorum when more than half of all known nodes are online in the same partition, or for the mathematically inclined, whenever the following equation is true:
total_nodes < 2 * active_nodes
For example, if a 5-node cluster split into 3- and 2-node paritions, the 3-node partition would have quorum and could continue serving resources. If a 6-node cluster split into two 3-node partitions, neither partition would have quorum; pacemaker’s default behavior in such cases is to stop all resources, in order to prevent data corruption.
Two-node clusters are a special case. By the above definition, a two-node cluster would only have quorum when both nodes are running. This would make the creation of a two-node cluster pointless, [7] but corosync has the ability to treat two-node clusters as if only one node is required for quorum.
The pcs cluster setup command will automatically configure two_node: 1 in corosync.conf, so a two-node cluster will «just work».
If you are using a different cluster shell, you will have to configure corosync.conf appropriately yourself. If you are using older versions of corosync, you will have to ignore quorum at the pacemaker level, using pcs property set no-quorum-policy=ignore (or the equivalent command if you are using a different cluster shell).

tl;dr если у тебя всего 2 ноды то нужно сделать следущее:

pcs property set no-quorum-policy=ignore

Deleted ()

Добрый день. Кластер работает все ок. Но при выключение двух нод, а затем включение master, сервисы на мастере не запускаются

а сколько всего нод?

upcFrost ★★★★★ ()

Да всего две ноды. Сейчас попробую указанный способ. Спасибо.

volkmen ()
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