The following should help with size estimation: http://search-lucene.com/?q=estimate+memory&fc_project=Solr
http://issues.apache.org/jira/browse/LUCENE-3435 I'll just add that with that much RAM you'll be more than fine. Otis ---- Sematext :: http://sematext.com/ :: Solr - Lucene - Nutch Lucene ecosystem search :: http://search-lucene.com/ >________________________________ >From: François Schiettecatte <fschietteca...@gmail.com> >To: solr-user@lucene.apache.org >Sent: Monday, September 26, 2011 12:43 PM >Subject: Re: drastic performance decrease with 20 cores > >You have not said how big your index is but I suspect that allocating 13GB for >your 20 cores is starving the OS of memory for caching file data. Have you >tried 6GB with 20 cores? I suspect you will see the same performance as 6GB & >10 cores. > >Generally it is better to allocate just enough memory to SOLR to run optimally >rather than as much as possible. 'Just enough' depends as well. You will need >to try out different allocations and see where the sweet spot is. > >Cheers > >François > > >On Sep 26, 2011, at 9:53 AM, Bictor Man wrote: > >> Hi everyone, >> >> Sorry if this issue has been discussed before, but I'm new to the list. >> >> I have a solr (3.4) instance running with 20 cores (around 4 million docs >> each). >> The instance has allocated 13GB in a 16GB RAM server. If I run several sets >> of queries sequentially in each of the cores, the I/O access goes very high, >> so does the system load, while the CPU percentage remains always low. >> It takes almost 1 hour to complete the set of queries. >> >> If I stop solr and restart it with 6GB allocated and 10 cores, after a bit >> the I/O access goes down and the CPU goes up, taking only around 5 minutes >> to complete all sets of queries. >> >> Meaning that for me is MUCH more performant having 2 solr instances running >> with half the data and half the memory than a single instance will all the >> data and memory. >> >> It would be even way faster to have 1 instance with half the cores/memory, >> run the queues, shut it down, start a new instance and repeat the process >> than having a big instance running everything. >> >> Furthermore, if I take the 20cores/13GB instance, unload 10 of the cores, >> trigger the garbage collector and run the sets of queries again, the >> behavior still remains slow taking like 30 minutes. >> >> am I missing something here? does solr change its caching policy depending >> on the number of cores at startup or something similar? >> >> Any hints will be very appreciated. >> >> Thanks, >> Victor > > > >
