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From Fran├žois Schiettecatte <>
Subject Re: Improving Solr performance
Date Fri, 07 Jan 2011 12:49:27 GMT
It sounds like your system is I/O bound and I suspect (bet even) that all your index files
are on the same disk drive. Also you have only 8GB of RAM for 100GB of index, so while your
SOLR instance will cache some stuff and the balance will be used for caching file blocks,
there really isn't enough memory there for effective caching.

I would suggest you check your machine's performance with something like atop (
) to see where your bottlenecks are (check the disk I/O). As I said I think you are I/O bound,
and if all your shards are on the same drive there will be I/O contention when running simultaneous

Your solutions are (in rough ascending order of cost):

- make your indices smaller (reduce disk I/O)

- buy more drives and spread your indices across the drives (reduce contention).

- buy more RAM (increase caching).

- buy more machines (more throughput).

Good luck!


On Jan 7, 2011, at 4:57 AM, supersoft wrote:

> have deployed a 5-sharded infrastructure where: shard1 has 3124422 docs
> shard2 has 920414 docs shard3 has 602772 docs shard4 has 2083492 docs shard5
> has 11915639 docs Indexes total size: 100GB
> The OS is Linux x86_64 (Fedora release 8) with vMem equal to 7872420 and I
> run the server using Jetty (from Solr example download) with: java -Xmx3024M
> -Dsolr.solr.home=multicore -jar start.jar
> The response time for a query is around 2-3 seconds. Nevertheless, if I
> execute several queries at the same time the performance goes down
> inmediately: 1 simultaneous query: 2516ms 2 simultaneous queries: 4250,4469
> ms 3 simultaneous queries: 5781, 6219, 6219 ms 4 simultaneous queries: 6484,
> 7203, 7719, 7781 ms...
> Using JConsole for monitoring the server java proccess I checked that Heap
> Memory and the CPU Usages don't reach the upper limits so the server
> shouldn't perform as overloaded. Can anyone give me an approach of how I
> should tune the instance for not being so hardly dependent of the number of
> simultaneous queries?
> Thanks in advance
> -- 
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