[GitHub] [zookeeper] maoling commented on a change in pull request #1661: ZOOKEEPER-3764: Add High Availability Guarantee Into Docs

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maoling commented on a change in pull request #1661:
URL: https://github.com/apache/zookeeper/pull/1661#discussion_r606646202



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File path: zookeeper-docs/src/main/resources/markdown/zookeeperAdmin.md
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@@ -321,14 +321,27 @@ machine in your deployment.
 
 For the ZooKeeper service to be active, there must be a
 majority of non-failing machines that can communicate with
-each other. To create a deployment that can tolerate the
-failure of F machines, you should count on deploying 2xF+1
-machines.  Thus, a deployment that consists of three machines
-can handle one failure, and a deployment of five machines can
-handle two failures. Note that a deployment of six machines
-can only handle two failures since three machines is not a
-majority.  For this reason, ZooKeeper deployments are usually
-made up of an odd number of machines.
+each other. For a ZooKeeper ensemble with N servers,
+if N is odd, the ensemble is able to tolerate up to N/2
+server failures without losing any znode data;
+if N is even, the ensemble is able to tolerate up to N/2-1
+server failures.
+
+For example, if we have a ZooKeeper ensemble with 3 servers,
+the ensemable is able to tolerate up to 1 (3/2) server failures.
+If we have a ZooKeeper ensemble with 5 servers,

Review comment:
       `ensemable` is a typo? other LGTM. 
   If no other concerns, I'll merge it at next weekend(04-10).
   




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