Home | About | Sematext search-lucene.com search-hadoop.com
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB
 Search Hadoop and all its subprojects:

Switch to Plain View
Hadoop >> mail # user >> Strange machine behavior


+
Robert Dyer 2012-12-09, 00:09
Copy link to this message
-
Re: Strange machine behavior
Oracle frequently recommends vm.swappiness = 0 to get well behaved RAC nodes.  Otherwise you start paging out things you don't usually want paged out in favor of a larger filesystem cache.

There is also a vm parameter that controls the minimum size of the free chain, might want to increase that a bit.

Also, look into hosting your JVM heap on huge pages, they can't be paged out and will help the JVM perform better too.

On Dec 8, 2012, at 6:09 PM, Robert Dyer <[EMAIL PROTECTED]> wrote:

> Has anyone experienced a TaskTracker/DataNode behaving like the attached image?
>
> This was during a MR job (which runs often).  Note the extremely high System CPU time.  Upon investigating I saw that out of 64GB ram the system had allocated almost 45GB to cache!
>
> I did a sudo sh -c "sync ; echo 3 > /proc/sys/vm/drop_cache ; sync" which is roughly where the graph goes back to normal (much lower System, much higher User).
>
> This has happened a few times.
>
> I have tried playing with the sysctl vm.swappiness value (default of 60) by setting it to 30 (which it was at when the graph was collected) and now to 10.  I am not sure that helps.
>
> Any ideas?  Anyone else run into this before?
>
> 24 cores
> 64GB ram
> 4x2TB sata3 hdd
>
> Running Hadoop 1.0.4, with a DataNode (2gb heap), TaskTracker (2gb heap) on this machine.
>
> 24 map slots (1gb heap each), no reducers.
>
> Also running HBase 0.94.2 with a RS (8gb ram) on this machine.
> <cpu-use.png>
+
ac@...) 2012-12-09, 11:45
+
Marcos Ortiz 2012-12-09, 01:05
+
Robert Dyer 2012-12-09, 02:10
+
Bharath Mundlapudi 2012-12-18, 08:42
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB