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From "Keith Turner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-4328) Run multiple tablet servers on a single host
Date Mon, 06 Jun 2016 16:33:21 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4328?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15316726#comment-15316726
] 

Keith Turner commented on ACCUMULO-4328:
----------------------------------------

In general I think bug fix releases with compatibility caveats are a bad thing over time.
 This can lead to a very confusing user experience.  I think these caveats are worse the further
a user is away from directly using Accumulo.  For users using Accumulo as part of a stack,
they primarily interact with the top of the stack (software built on top of Accumulo).  When
someone is trying to use something like Geowave, its nice to know that version 1.X.ANY of
Geowave works with Accumulo 1.6.ANY.  Ideally a user of something like Geowave could move
between the bug fix release of Hadoop, Accumulo, and Zookeeper w/o issue.  The stories about
Hadoop in this issue make me cringe, but there is nothing we can do about that.  I would hope
the incremental decision we make in the short term also make sense in the long term.  If we
fast forward a few years and look at all of the 1.7.X release notes, hopefully it looks very
orderly and sane.

Recently there was some major issue with Zookeeper 3.4.7.  When the issue was discovered the
remedy was for users to move back to 3.4.6 until 3.4.8 was released.  Its really nice to have
that level of flexibility w/ bug fix releases, the ability to move in both directions w/o
worry.

Also I am not a big fan of one off exceptions, because they can be time sinks (like me currently
sharing my opinions, that I am not sure anyone will fully read.. I am doing my best to keep
it short and to the point).  Personally I would rather drop it in the latest minor release.
 A really strong case needs to be made for exceptions.   Like in this case there does not
seem to be performance numbers.  Also the implementation (using PIDs in log files) has raised
concern.  Seem like these issues should be addressed before we consider putting this in a
bug fix release.  I am going to look into the file per tserver issue when I look at the PR
(I did this locally once, where each tserver had its own log file).

I am excited about this feature.  I tend to think multiple tservers can perform much better,
simply because when a node had oodles of disk and cores there is no way a single walog can
utilize all of that capacity.   However I think that premise needs to be verified and ensure
there are not unforeseen issues with attaining higher utilization.



> Run multiple tablet servers on a single host
> --------------------------------------------
>
>                 Key: ACCUMULO-4328
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4328
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: scripts, tserver
>            Reporter: Dave Marion
>            Assignee: Dave Marion
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Modify scripts and necessary code to run multiple tablet servers on a single host.



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