On 4/19/2013 2:15 AM, David Parks wrote: > Interesting. I'm trying to correlate this new understanding to what I see on > my servers. I've got one server with 5GB dedicated to solr, solr dashboard > reports a 167GB index actually. > > When I do many typical queries I see between 3MB and 9MB of disk reads > (watching iostat). > > But solr's dashboard only shows 710MB of memory in use (this box has had > many hundreds of queries put through it, and has been up for 1 week). That > doesn't quite correlate with my understanding that Solr would cache the > index as much as possible.
There are two memory sections on the dashboard. The one at the top shows the operating system view of physical memory. That is probably showing virtually all of it in use. Most UNIX platforms will show you the same info with 'top' or 'free'. Some of them, like Solaris, require different tools. I assume you're not using Windows, because you mention iostat. The other memory section is for the JVM, and that only covers the memory used by Solr. The dark grey section is the amount of Java heap memory currently utilized by Solr and its servlet container. The light grey section represents the memory that the JVM has allocated from system memory. If any part of that bar is white, then Java has not yet requested the maximum configured heap. Typically a long-running Solr install will have only dark and light grey, no white. The operating system is what caches your index, not Solr. The bulk of your RAM should be unallocated. With your index size, the OS will use all unallocated RAM for the disk cache. If a program requests some of that RAM, the OS will instantly give it up. Thanks, Shawn
