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https://issues.apache.org/jira/browse/OOZIE-1561?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13795672#comment-13795672
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Robert Kanter commented on OOZIE-1561:
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Getting back to the HA logs discussion...
I'm not sure if this really helps us, but we technically only need to make the
log messages that have a job ID in them HA because other log messages would
never be asked for.
I originally thought idea 2 made the most sense but I think it would be very
tricky to do. If HDFS goes down, we either have to "pause" all Oozie work or
we have to temporarily write the logs locally and then upload them once HDFS
comes back. We don't really gain very much over idea 1 because we'd still have
to keep the current behavior of streaming between the servers for this case.
We might as well then just do idea 1, which will be easier to implement and
less fragile. So, I'm now thinking that idea 1 makes the most sense. Thoughts?
Also, both idea 1 and idea 2 don't have to be tied to Oozie HA. I think that
in either case, we should make it independent and the user can enable/disable
this.
> When using Oozie HA, the logs should also be HA
> -----------------------------------------------
>
> Key: OOZIE-1561
> URL: https://issues.apache.org/jira/browse/OOZIE-1561
> Project: Oozie
> Issue Type: Improvement
> Components: HA
> Affects Versions: trunk
> Reporter: Robert Kanter
> Assignee: Robert Kanter
> Priority: Critical
>
> Currently, if an Oozie server goes down, the logs from that server become
> unavailable until the server comes back up. In the meantime, the user may or
> may not be aware that log messages could be missing when Oozie streams logs
> to the user.
> We should come up with a way to make the logs HA.
> Some ideas:
> # When rolling the logs, copy them into HDFS; Oozie servers can then read the
> log files directly from HDFS instead of each other
> #- The downside to this is that there will be a window where logs could still
> be missing as they only show up in HDFS after rolling over (default = 1hr)
> and Oozie servers would still have to contact each other for the last hour of
> logs
> #- The upside is that it minimizes the amount of logs that could be missing
> and would be fairly straightforward to implement
> # Log directly to HDFS
> #- The downside is that this may be complicated or tricky to get working
> properly
> #-- This also introduces a strict dependency on HDFS
> #- The upside is that this would completely solve the issue and Oozie servers
> would simply get all logs directly from HDFS
> # Log to ZooKeeper or a database
> #- I think the log files will be too big to do this
> I've assigned this to myself, but if someone wants to tackle this, feel free
> to reassign it. I think idea 2 is the most practical, but I'm also open to
> other ideas on how to do this.
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