[
https://issues.apache.org/jira/browse/HDFS-3077?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13471673#comment-13471673
]
Sanjay Radia commented on HDFS-3077:
------------------------------------
bq. To be perfectly frank, I'm not interested in changing the design
substantially ...
Todd the change is small and i am trying to help you here. Recall in HDFS-1073
you did not want to use transaction ids or name the log files using transaction
id range and you argued against this for quite a while. As I predicted, txids
have become a cornerstone of HA and managing journals.
The only real change I have proposed to the protocol is to merge the first 2
operations.
* You have argued that prepare-recovery, using the epoch number from previous
newEpoch, is like multi-paxos - not sure if multi-paxos is warranted here.
* The response of the newEpoch() is highest txId while response to
PrepareRecovery is the state of the highest segment, and optionally additional
info if there was a previous recovery in progress.
* BTW I am okay with the document describing the protocol by mapping it to both
paxos and zab for the reader.
> Quorum-based protocol for reading and writing edit logs
> -------------------------------------------------------
>
> Key: HDFS-3077
> URL: https://issues.apache.org/jira/browse/HDFS-3077
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: ha, name-node
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: QuorumJournalManager (HDFS-3077)
>
> Attachments: hdfs-3077-partial.txt, hdfs-3077-test-merge.txt,
> hdfs-3077.txt, hdfs-3077.txt, hdfs-3077.txt, hdfs-3077.txt, hdfs-3077.txt,
> hdfs-3077.txt, hdfs-3077.txt, qjournal-design.pdf, qjournal-design.pdf,
> qjournal-design.pdf, qjournal-design.pdf, qjournal-design.pdf,
> qjournal-design.pdf, qjournal-design.tex, qjournal-design.tex
>
>
> Currently, one of the weak points of the HA design is that it relies on
> shared storage such as an NFS filer for the shared edit log. One alternative
> that has been proposed is to depend on BookKeeper, a ZooKeeper subproject
> which provides a highly available replicated edit log on commodity hardware.
> This JIRA is to implement another alternative, based on a quorum commit
> protocol, integrated more tightly in HDFS and with the requirements driven
> only by HDFS's needs rather than more generic use cases. More details to
> follow.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
