[jira] [Commented] (AMQ-4987) io wait on replicated levelDB slaves

["anselme dewavrin (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AMQ-4987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14047684#comment-14047684 ] 

anselme dewavrin commented on AMQ-4987:
---------------------------------------

still up and running in production.

> io wait on replicated levelDB slaves
> ------------------------------------
>
>                 Key: AMQ-4987
>                 URL: https://issues.apache.org/jira/browse/AMQ-4987
>             Project: ActiveMQ
>          Issue Type: Test
>          Components: activemq-leveldb-store
>    Affects Versions: 5.9.0
>         Environment: debian VM 2.6.32-5-amd64, jdk7
>            Reporter: anselme dewavrin
>            Priority: Minor
>             Fix For: 5.9.0
>
>
> Dear all,
> I set up a 3-nodes replicatedLevelDB activeMQ cluster on 3 different machines, as explained on the activemq site (with zookeeper etc.).
> I made a message injector using the php stomp client described here : http://stomp.fusesource.org/documentation/php/book.html
> Then I injected persistent messages as fast as possible (giving about 100 messages/s, each message is 10k).
> Everything works fine, then I measured the servers' activity with "vmstat 1". I saw no iowait on the master node, but  20% on both slaves. This would impeach scalabitity I suppose. And the iowait is justified by 3000 bo/s (blocks out) in the vmstat report.
> The machines are not swapping (paging).
> Here is what I tried, without success :
> -specify explicitly sync="quorum_mem"
> -JNI implementation of the leveldb store (and verified it is used)
> -setting flushDelay to 2000
> Does anyone have an idea that I could try ? Why is the leveldb slaves writing so much to disk ?
> Many thanks in advance
> Yours,
> Anselme



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