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From "Nitay Joffe (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-1145) Ensure that there is only 1 Master with Zookeeper
Date Sat, 31 Jan 2009 21:47:59 GMT

    [ https://issues.apache.org/jira/browse/HBASE-1145?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12669261#action_12669261
] 

Nitay Joffe commented on HBASE-1145:
------------------------------------

Eventually, the leader election described above is the way to go. Then any regionservers can
assume the master role and there are no special master servers. That implementation requires
a lot of heavy changes, so for right now we are going to just do a master lock.

Users will spin up multiple masters, and they will race to grab the master lock in ZooKeeper.
Whoever grabs it creates the ephemeral node and writes their server address to the ZNode.
The rest of the masters will sit around waiting for the ephemeral node to go away (master
goes down) and then the race repeats.

Region servers and clients will go to this location in ZooKeeper to get the master address.
This means we can get rid of the hbase.master property in hbase-site.xml. To retain the option
of running in "local" mode, we will add a "run.distributed" property to the hbase-site.xml
which defaults to false. For backwards compatibility, if users have their hbase.master set
to something other than "local", we can override the run.distributed option and produce a
warning that the "hbase.master" option is going away and they should update their hbase-site.xml
with the new "run.distributed" property.

Thoughts?

> Ensure that there is only 1 Master with Zookeeper
> -------------------------------------------------
>
>                 Key: HBASE-1145
>                 URL: https://issues.apache.org/jira/browse/HBASE-1145
>             Project: Hadoop HBase
>          Issue Type: Sub-task
>            Reporter: Jean-Daniel Cryans
>            Assignee: Nitay Joffe
>


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