# Load balancing and a node with no primary shard **URL:** \ **Category:** Elasticsearch\ **Created:** [January 2, 2014, 12:34pm UTC](https://discuss.elastic.co/t/load-balancing-and-a-node-with-no-primary-shard/15078 "2014-01-02T12:34:16Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Guy\_Aharoni](https://avatars.discourse-cdn.com/v4/letter/g/ee7513/32.png) [@Guy\_Aharoni](https://discuss.elastic.co/u/Guy_Aharoni)\ **Post date:** [January 2, 2014, 12:34pm UTC](https://discuss.elastic.co/t/load-balancing-and-a-node-with-no-primary-shard/15078/1 "2014-01-02T12:34:16Z")
Hi, We have a system based on Elasticsearch and we're performing volume tests in order to come up with hardware requirements. Following the tests, I am confused by the role of the primary shard in a load balanced environment and am wondering regarding performance after a node failure. I also have issues with ES\_MAX\_MEM. Can you please help? In my lab I have two data nodes and one client node (non-data), configured for two shards and one replica. My client is sending Index requests to the client node. ES\_MAX\_MEM=ES\_MIN\_MEM=8g and eace node has 16GB RAM. In the volume tests we sent a steady stream of messages to ES (12,500 messages every 5 seconds). During testing I closed one of the data nodes and as a result the other node showed it's two shards are primary shards. When the first node came back up all turned green, but the second node still held both primary shards. The other thing that happened is the elasticseach memory consumption constantly grew until it consumed the entire 16GB RAM. 1. Shouldn't adding a new node result in splitting primary shards between all nodes? How come one of the shards in the first node did not become a primary share? 2. Since the client node is load balancing, what happens when it sends data to the node which has no primary shard? Does that impact performance? 3. How come ES consumed 16GBRAM when ES\_MAX\_MEM is set to 8g? Thanks, Guy -- 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). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/1de23735-5b44-49b3-8e2a-96ecdc362f14%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/1de23735-5b44-49b3-8e2a-96ecdc362f14%40googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [January 2, 2014, 2:15pm UTC](https://discuss.elastic.co/t/load-balancing-and-a-node-with-no-primary-shard/15078/2 "2014-01-02T14:15:08Z")
1. What you observe is correct. Replica shards can be instantly promoted to primary shards. Primary shards stay as long as the node is running. The reason is, there is no functional difference between a primary and replica. You should not worry about primary shards at all, they do not matter for load balancing. 2. Each node is able to route any index request, over the whole cluster, whether it holds primary shards or not. All nodes that hold shards of an index will receive index requests. The primary first, the others next. Only the order is different, not the resulting indexing load. 3. ES\_MAX\_MEM is not limiting the maximum memory of the process. It is the maximum heap memory for the JVM. Beside the heap, the JVM allocates other memory spaces, direct buffer memory, or caches. Jörg -- 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). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAKdsXoHo09zMa%3Dj%3DoMgE4FRkR7\_8pacDGH%3D5xNU3JvtdFYxawg%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAKdsXoHo09zMa%3Dj%3DoMgE4FRkR7_8pacDGH%3D5xNU3JvtdFYxawg%40mail.gmail.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, 1:58am UTC](https://discuss.elastic.co/t/load-balancing-and-a-node-with-no-primary-shard/15078/3 "2017-07-06T01:58:41Z")