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https://issues.apache.org/jira/browse/ZOOKEEPER-1016?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13006857#comment-13006857
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Ivan Kelly commented on ZOOKEEPER-1016:
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They have definite overlap, both may or may not solve the same problem. This
could be implemented using ZOOKEEPER-1001 as the mechanism for getting the
replicated logs to the secondaries. This also proposes a mechanism where the
primary sends the entries directly to the secondaries. The advantage of the
second approach is that less data will be sent over the network. As I
understand it, with ZOOKEEPER-1001 each reader has to read from all bookies and
merge the entries returned. This will result in 100% more data transfer than
required, as each entry will be read from at least 2 bookies. With the solution
above, each entry is only sent to the secondary once.
> TeaKeeper: Hot standby support using bookkeeper
> -----------------------------------------------
>
> Key: ZOOKEEPER-1016
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1016
> Project: ZooKeeper
> Issue Type: Improvement
> Reporter: Ivan Kelly
> Assignee: Ivan Kelly
> Priority: Minor
> Attachments: tledger.pdf
>
>
> Currently Bookkeeper provides functionality for cold backups. If the entity
> logging to bookkeeper fails, its replacement must recover the ledgers which
> had been used for backup before becoming available. This is acceptable in
> some cases, such as HBase Wals where a small delay in recovery only results
> in a small percentage of data being unavailable.
> However, systems such as the HDFS namenode, this delay can be unacceptable,
> such as cases where data is being served to customers. Secondary namenodes
> should be ready to go the instant the primary goes down.
> TeaKeeper proposes a wrapper library around Bookkeeper providing T-Junction
> like functionality for logging. It also provides for primary/secondary
> election and automated hot failover.
> HDFS namenode is primary target of this work.
> The attached design doc contains more details.
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