php - Does the galera cluster have to have an even number of nodes? -

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i have 8 nodes in galera cluster, saw video suggests have odd number of nodes (3,5,7,9,ect).

is true? , have issues having 8 nodes in cluster?

no, 8 ok. "quorum" mechanism needs majority. if have @ least 3 nodes (and 1 fails), remaining nodes can establish quorum.

if 8 nodes split 4 in each of 2 datacenters, datacenter outage kill entire cluster. protect against datacenter failure, should spread nodes 'evenly' across 3 (or more) datacenters. 8 nodes: 3+3+2 safe split. 4+3+1 or 4+2+2 kill cluster if '4' datacenter went down.

how 8-node cluster working? (that's biggest 1 have heard of.)


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