Update highly-available-master.md (#5006)

* Update highly-available-master.md
This commit is contained in:
Anthony
2017-08-25 00:41:07 +08:00
committed by Jessica Yao
parent 1d06ea0095
commit e8029bdc4e
@@ -92,11 +92,11 @@ $ KUBE_GCE_ZONE=replica-zone KUBE_REPLICATE_EXISTING_MASTER=true ./cluster/kube-
## Best practices for replicating masters for HA clusters ## Best practices for replicating masters for HA clusters
* Try to place masters replicas in different zones. During a zone failure, all master placed inside the zone will fail. * Try to place master replicas in different zones. During a zone failure, all masters placed inside the zone will fail.
To survive zone failure, also place nodes in multiple zones To survive zone failure, also place nodes in multiple zones
(see [multiple-zones](/docs/admin/multiple-zones/) for details). (see [multiple-zones](/docs/admin/multiple-zones/) for details).
* Do not use a cluster with two master replicas. Consensus on a two replica cluster requires both replicas running when changing persistent state. * Do not use a cluster with two master replicas. Consensus on a two-replica cluster requires both replicas running when changing persistent state.
As a result, both replicas are needed and a failure of any replica turns cluster into majority failure state. As a result, both replicas are needed and a failure of any replica turns cluster into majority failure state.
A two-replica cluster is thus inferior, in terms of HA, to a single replica cluster. A two-replica cluster is thus inferior, in terms of HA, to a single replica cluster.