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Posted to notifications@zookeeper.apache.org by GitBox <gi...@apache.org> on 2021/03/29 02:22:11 UTC
[GitHub] [zookeeper] Winbobob opened a new pull request #1661: ZOOKEEPER-3764: Add High Availability Guarantee Into Docs
Winbobob opened a new pull request #1661:
URL: https://github.com/apache/zookeeper/pull/1661
Include the formula for calculating the maximum number of server failures in the ZK doc.
> https://issues.apache.org/jira/browse/ZOOKEEPER-3764
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[GitHub] [zookeeper] asfgit closed pull request #1661: ZOOKEEPER-3764: Add High Availability Guarantee Into Docs
Posted by GitBox <gi...@apache.org>.
asfgit closed pull request #1661:
URL: https://github.com/apache/zookeeper/pull/1661
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[GitHub] [zookeeper] maoling commented on a change in pull request #1661: ZOOKEEPER-3764: Add High Availability Guarantee Into Docs
Posted by GitBox <gi...@apache.org>.
maoling commented on a change in pull request #1661:
URL: https://github.com/apache/zookeeper/pull/1661#discussion_r610998480
##########
File path: zookeeper-docs/src/main/resources/markdown/zookeeperAdmin.md
##########
@@ -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 ensemble is able to tolerate up to 1 (3/2) server failures.
+If we have a ZooKeeper ensemble with 5 servers,
+the ensemble is able to tolerate up to 2 (5/2) server failures.
+If the ZooKeeper ensemble with 6 servers, the ensemble
+is also able to tolerate up to 2 (6/2-1) server failures
Review comment:
@belugabehr Look at the [explanation](https://issues.apache.org/jira/browse/ZOOKEEPER-3764?focusedCommentId=17315975&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17315975). I prefer to `(6/2-1)`.
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[GitHub] [zookeeper] Winbobob commented on a change in pull request #1661: ZOOKEEPER-3764: Add High Availability Guarantee Into Docs
Posted by GitBox <gi...@apache.org>.
Winbobob commented on a change in pull request #1661:
URL: https://github.com/apache/zookeeper/pull/1661#discussion_r606679311
##########
File path: zookeeper-docs/src/main/resources/markdown/zookeeperAdmin.md
##########
@@ -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:
Thank you, just fixed the typo!
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[GitHub] [zookeeper] maoling commented on a change in pull request #1661: ZOOKEEPER-3764: Add High Availability Guarantee Into Docs
Posted by GitBox <gi...@apache.org>.
maoling commented on a change in pull request #1661:
URL: https://github.com/apache/zookeeper/pull/1661#discussion_r606646202
##########
File path: zookeeper-docs/src/main/resources/markdown/zookeeperAdmin.md
##########
@@ -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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[GitHub] [zookeeper] belugabehr commented on a change in pull request #1661: ZOOKEEPER-3764: Add High Availability Guarantee Into Docs
Posted by GitBox <gi...@apache.org>.
belugabehr commented on a change in pull request #1661:
URL: https://github.com/apache/zookeeper/pull/1661#discussion_r607873580
##########
File path: zookeeper-docs/src/main/resources/markdown/zookeeperAdmin.md
##########
@@ -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 ensemble is able to tolerate up to 1 (3/2) server failures.
+If we have a ZooKeeper ensemble with 5 servers,
+the ensemble is able to tolerate up to 2 (5/2) server failures.
+If the ZooKeeper ensemble with 6 servers, the ensemble
+is also able to tolerate up to 2 (6/2-1) server failures
Review comment:
Is this supposed to be `(6-1)/2` or `((6/2)-1)` ?
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