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Hadoop >> mail # user >> NameNode heapsize


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Re: NameNode heapsize

On Jun 10, 2011, at 6:32 AM, [EMAIL PROTECTED] wrote:

> Dear all,
>
> I'm looking for ways to improve the namenode heap size usage of a 800-node 10PB testing Hadoop cluster that stores
> around 30 million files.
>
> Here's some info:
>
> 1 x namenode:     32GB RAM, 24GB heap size
> 800 x datanode:   8GB RAM, 13TB hdd
>
> *33050825 files and directories, 47708724 blocks = 80759549 total. Heap Size is 22.93 GB / 22.93 GB (100%) *
>
> From the cluster summary report, it seems the heap size usage is always full but couldn't drop, do you guys know of any ways
> to reduce it ? So far I don't see any namenode OOM errors so it looks memory assigned for the namenode process is (just)
> enough. But i'm curious which factors would account for the full use of heap size ?
>

The advice I give to folks is to plan on 1GB heap for every million objects.  It's an over-estimate, but I prefer to be on the safe side.  Why not increase the heap-size to 28GB?  Should buy you some time.

You can turn on compressed pointers, but your best bet is really going to be spending some more money on RAM.

Brian
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