Hi,
When it is time to calculate how much RAM a solr instance needs to run with good performance, I know that it is some form of art, but I'm looking at a general "formula" to have at least one good starting point. Apart the RAM devoted to Java HEAP, that is strongly dependant on how I configure caches, and the distribution of queries in my system, I'm particularly interested in the amount of RAM to leave to operating system to use File Cache. Suppose I have an index of 51 Gb of dimension, clearly having that amount of ram devoted to the OS is the best approach, so all index files can be cached into memory by the OS, thus I can achieve maximum speed. But if I look at the detail of the index, in this particular example I see that the bigger file has .fdt extension, it is the stored field for the documents, so it affects retrieval of document data, not the real search process. Since this file is 24 GB of size, it is almost half of the space of the index. My question is: it could be safe to assume that a good starting point for the amount of RAM to leave to the OS is the dimension of the index less the dimension of the .fdt file because it has less importance in the search process? Are there any particular setting at OS level (CentOS linux) to have maximum benefit from OS file cache? (documentation at <https://cwiki.apache.org/confluence/display/solr/Taking+Solr+to+Production# TakingSolrtoProduction-MemoryandGCSettings> https://cwiki.apache.org/confluence/display/solr/Taking+Solr+to+Production#T akingSolrtoProduction-MemoryandGCSettings does not have any information related to OS configuration). Elasticsearch (https://www.elastic.co/guide/en/elasticsearch/reference/1.4/setup-configura tion.html) generally have some suggestions such as using mlockall, disable swap etc etc, I wonder if there are similar suggestions for solr. Many thanks for all the great help you are giving me in this mailing list. -- Gian Maria Ricci Cell: +39 320 0136949 <http://mvp.microsoft.com/en-us/mvp/Gian%20Maria%20Ricci-4025635> <http://www.linkedin.com/in/gianmariaricci> <https://twitter.com/alkampfer> <http://feeds.feedburner.com/AlkampferEng>
