bq: You should have memory to fit your whole database in disk cache and then some more.
I have to disagree here if for no other reason than stored data, which is irrelevant for searching, may make up virtually none or virtually all of your on-disk space. Saying it all needs to fit in disk cache is too broad-brush a statement, gotta test. In this case, though, I _do_ think that there's not enough memory here, Toke's comments are spot on. On Sat, Nov 29, 2014 at 2:02 AM, Toke Eskildsen <t...@statsbiblioteket.dk> wrote: > Po-Yu Chuang [ratbert.chu...@gmail.com] wrote: >> [...] Everything works fine now, but I noticed that the load >> average of the server is high because there is constantly >> heavy disk read access. Please point me some directions. > >> RAM: 18G >> Solr home: 185G >> disk read access constantly 40-60M/s > > Solr search performance is tightly coupled to the speed of small random > reads. There are two obvious ways of ensuring that in these days: > > 1) Add more RAM to the server, so that the disk cache can hold a larger part > of the index. If you add enough RAM (depends on your index, but 50-100% of > the index size is a rule of thumb), you get "ideal" storage speed, by which I > mean that the bottleneck moves away from storage. If you are using spinning > drives, the 18GB of RAM is not a lot for a 185GB index. > > 2) Use SSDs instead of spinning drives (if you do not already do so). The > speed-up depends a lot on what you are doing, but is is a cheap upgrade and > it can later be coupled with extra RAM if it is not enough in itself. > > The Solr Wiki has this: https://wiki.apache.org/solr/SolrPerformanceProblems > And I have this: http://sbdevel.wordpress.com/2013/06/06/memory-is-overrated/ > > - Toke Eskildsen
