# ES RAM requirement **URL:** \ **Category:** Elasticsearch\ **Created:** [July 18, 2013, 2:29pm UTC](https://discuss.elastic.co/t/es-ram-requirement/12843 "2013-07-18T14:29:02Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Anand\_Nalya](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/anand_nalya/32/571_2.png) [@Anand\_Nalya](https://discuss.elastic.co/u/Anand_Nalya)\ **Post date:** [July 18, 2013, 2:29pm UTC](https://discuss.elastic.co/t/es-ram-requirement/12843/1 "2013-07-18T14:29:02Z")
Hi, I understand that search performance for ES is directly affected by the available RAM. but I still want to know what all steps can be taken to decrease the amount of RAM requirements. Generally what is the ration of RAM/Index Size has been observed in production. Regards, Anand -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![radu\_gheorghe](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/radu_gheorghe/32/556_2.png) [@radu\_gheorghe](https://discuss.elastic.co/u/radu_gheorghe)\ **Post date:** [July 18, 2013, 3:49pm UTC](https://discuss.elastic.co/t/es-ram-requirement/12843/2 "2013-07-18T15:49:37Z")
Hello Anand, Yes, your search performance will probably depend a lot on the RAM you have available. Unfortunately, at least I can't give you a RAM/Index\_size ratio, not even a rough one, because that would depend heavily on: - how often your indices are hit by searches - how complex the searches are - how your documents look like (how many fields, how they're analyzed...) Regarding memory itself, there are two things: - the memory ES uses. This is where it's important to give the JVM enough room for Elasticsearch's needs, otherwise the Garbage Collector will eat your CPU "recycling your RAM" all the time. And, especially if you searches are heavy, you want CPU to take care of searches, instead of GC - the memory OS caches use. Because you don't want ES to hit your disk continuously to get indexed data, the OS caches it. The more of your ES index can fit in your "free" RAM, the faster your searches will be. If your indices are waaay larger than your RAM, and I/O seems to be a bottleneck, SSDs may be a good option Back to your RAM question, here's what I would do: - take the data set you want to search on and put it in a test cluster. Or a portion of that data, with a portion of what might be your production cluster - allocate 50% of your RAM to ES. That's usually a good start - run some tests that load your test cluster as you expect a production cluster to be loaded - monitor the cluster with some monitoring tool like our SPM[http://sematext.com/spm/elasticsearch-performance-monitoring/](http://sematext.com/spm/elasticsearch-performance-monitoring/) - check out how much memory your JVM uses. It will go up and down, but you'll get a rough idea. For example, let's say you have 32GB of RAM in total, and you've allocated 16 to ES initially. And you notice that your average memory usage for the JVM is about 5GB. In this case, you'll probably be better off lowering ES\_HEAP\_SIZE to 10 or maybe 8 GB, and leave more room for OS caches. On the other hand, if you see the GC running often, and your memory usage going up and down close to your 16GB limit, it's a sign that ES needs more RAM. You can also dig deeper into what eats your RAM. If you use filters a lot, ES will rely on filter caches. If you sort or facet a lot, ES will rely on field caches. You can look at how these caches are used in SPM and tweak them in the ES configuration. ## Best regards, Radu [http://sematext.com/](http://sematext.com/) -- Elasticsearch -- Solr -- Lucene On Thu, Jul 18, 2013 at 5:29 PM, Anand Nalya [anand.nalya@gmail.com](mailto:anand.nalya@gmail.com) wrote: > Hi, > > I understand that search performance for ES is directly affected by the > available RAM. but I still want to know what all steps can be taken to > decrease the amount of RAM requirements. > > Generally what is the ration of RAM/Index Size has been observed in > production. > > Regards, > Anand > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 2:25am UTC](https://discuss.elastic.co/t/es-ram-requirement/12843/3 "2017-07-06T02:25:43Z")