Todd Lipcon created HDFS-3743:
---------------------------------
Summary: QJM: improve formatting behavior for JNs
Key: HDFS-3743
URL: https://issues.apache.org/jira/browse/HDFS-3743
Project: Hadoop HDFS
Issue Type: Sub-task
Affects Versions: QuorumJournalManager (HDFS-3077)
Reporter: Todd Lipcon
Assignee: Todd Lipcon
Currently, the JournalNodes automatically format themselves when a new writer takes over,
if they don't have any data for that namespace. However, this has a few problems:
1) if the administrator accidentally points a new NN at the wrong quorum (eg corresponding
to another cluster), it will auto-format a directory on those nodes. This doesn't cause any
data loss, but would be better to bail out with an error indicating that they need to be formatted.
2) if a journal node crashes and needs to be reformatted, it should be able to re-join the
cluster and start storing new segments without having to fail over to a new NN.
3) if 2/3 JNs get accidentally reformatted (eg the mount point becomes undone), and the user
starts the NN, it should fail to start, because it may end up missing edits. If it auto-formats
in this case, the user might have silent "rollback" of the most recent 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
|