[
https://issues.apache.org/jira/browse/HDFS-3092?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13245523#comment-13245523
]
Suresh Srinivas commented on HDFS-3092:
---------------------------------------
bq. When you say three JDs, that's the degree of replication, right? When I
said multiple logs, I was referring to multiple namenodes writing to different
logs, as with federation.
Right, three JDs for degree of replication. However, I do understand multiple
logs - that is a log per namespace. For every namespace, in federation, active
and standby namenode + additional JD is needed.
bq. I think my confusion here is that you require a quorum to be able to
acknowledge the operation, but in reality you try to write to everyone. If you
can't write to everyone, then you induce a view change (change to JournalList).
Is this right?
Yes. In the first cut we write to all the JDs that are active. At least quorum
should be written. This can be improved in the future by waiting for only
Quorum JDs.
> Enable journal protocol based editlog streaming for standby namenode
> --------------------------------------------------------------------
>
> Key: HDFS-3092
> URL: https://issues.apache.org/jira/browse/HDFS-3092
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: ha, name-node
> Affects Versions: 0.24.0, 0.23.3
> Reporter: Suresh Srinivas
> Assignee: Suresh Srinivas
> Attachments: MultipleSharedJournals.pdf
>
>
> Currently standby namenode relies on reading shared editlogs to stay current
> with the active namenode, for namespace changes. BackupNode used streaming
> edits from active namenode for doing the same. This jira is to explore using
> journal protocol based editlog streams for the standby namenode. A daemon in
> standby will get the editlogs from the active and write it to local edits. To
> begin with, the existing standby mechanism of reading from a file, will
> continue to be used, instead of from shared edits, from the local edits.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
