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anselme dewavrin updated AMQ-4987: ---------------------------------- Description: 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 was: Dear all, I set up a 3-nodes replicatedLevelDB activeMQ cluster as explained on the activemq site. 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 > 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 > > 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 -- This message was sent by Atlassian JIRA (v6.1.5#6160)