# Performance question about shards and replicas **URL:** \ **Category:** Elasticsearch\ **Created:** [February 10, 2014, 10:22am UTC](https://discuss.elastic.co/t/performance-question-about-shards-and-replicas/15690 "2014-02-10T10:22:26Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Valentin\_Pletzer](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/valentin_pletzer/32/105548_2.png) [@Valentin\_Pletzer](https://discuss.elastic.co/u/Valentin_Pletzer)\ **Post date:** [February 10, 2014, 10:22am UTC](https://discuss.elastic.co/t/performance-question-about-shards-and-replicas/15690/1 "2014-02-10T10:22:26Z")
Hi, I use elasticsearch for logfile analysis. I use rolling indeces on a daily basis. I use 2 elasticsearch-servers behind a loadbalancer. The data is sent to the load balancer and then inserted on the according server. I use 1 index with 1 shard and 1 replica. So there is "one file" on both server. The data is queried through the load balancer as well. And I am always querying the current day and the same day last week. My question now is: Would it be better to use a daily index with 2 or more shards? Greetings, Valentin -- 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/3b3fb4ff-0bc1-4b83-ac2d-d421d6f8ad06%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/3b3fb4ff-0bc1-4b83-ac2d-d421d6f8ad06%40googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [February 10, 2014, 10:44am UTC](https://discuss.elastic.co/t/performance-question-about-shards-and-replicas/15690/2 "2014-02-10T10:44:41Z")
I'd add another node into the cluster to allow easier quorum and prevent split brain. Then split the index into (at least) 3 shards to spread the load. Ideally you want to try to get one shard per node. Regards, Mark Walkom Infrastructure Engineer Campaign Monitor email: [markw@campaignmonitor.com](mailto:markw@campaignmonitor.com) web: [www.campaignmonitor.com](http://www.campaignmonitor.com) On 10 February 2014 21:22, Valentin [pletzer@gmail.com](mailto:pletzer@gmail.com) wrote: > Hi, > > I use elasticsearch for logfile analysis. I use rolling indeces on a daily > basis. I use 2 elasticsearch-servers behind a loadbalancer. The data is > sent to the load balancer and then inserted on the according server. I use > 1 index with 1 shard and 1 replica. So there is "one file" on both server. > The data is queried through the load balancer as well. And I am always > querying the current day and the same day last week. > > My question now is: Would it be better to use a daily index with 2 or more > shards? > > Greetings, > Valentin > > -- > 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/3b3fb4ff-0bc1-4b83-ac2d-d421d6f8ad06%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/3b3fb4ff-0bc1-4b83-ac2d-d421d6f8ad06%40googlegroups.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). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAEM624bHQYFjzn3NPVoq9y1K2ziEo9qqzuDRSW5MvPnythdxtQ%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAEM624bHQYFjzn3NPVoq9y1K2ziEo9qqzuDRSW5MvPnythdxtQ%40mail.gmail.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![Valentin\_Pletzer](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/valentin_pletzer/32/105548_2.png) [@Valentin\_Pletzer](https://discuss.elastic.co/u/Valentin_Pletzer)\ **Post date:** [February 10, 2014, 4:01pm UTC](https://discuss.elastic.co/t/performance-question-about-shards-and-replicas/15690/3 "2014-02-10T16:01:01Z")
Thanks. The split brain problem aside: Is it faster for elasticsearch to read a shard than a replica? On Monday, February 10, 2014 11:44:41 AM UTC+1, Mark Walkom wrote: > I'd add another node into the cluster to allow easier quorum and prevent > split brain. > Then split the index into (at least) 3 shards to spread the load. Ideally > you want to try to get one shard per node. > > Regards, > Mark Walkom > > Infrastructure Engineer > Campaign Monitor > email: [ma...@campaignmonitor.com](mailto:ma...@campaignmonitor.com) \ > web: [www.campaignmonitor.com](http://www.campaignmonitor.com) > > On 10 February 2014 21:22, Valentin \<[ple...@gmail.com](mailto:ple...@gmail.com) \\>wrote: > > > Hi, > > > > I use elasticsearch for logfile analysis. I use rolling indeces on a > > daily basis. I use 2 elasticsearch-servers behind a loadbalancer. The data > > is sent to the load balancer and then inserted on the according server. I > > use 1 index with 1 shard and 1 replica. So there is "one file" on both > > server. The data is queried through the load balancer as well. And I am > > always querying the current day and the same day last week. > > > > My question now is: Would it be better to use a daily index with 2 or > > more shards? > > > > Greetings, > > Valentin > > > > -- > > 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 [elasticsearc...@googlegroups.com](mailto:elasticsearc...@googlegroups.com) \. > > To view this discussion on the web visit > > [https://groups.google.com/d/msgid/elasticsearch/3b3fb4ff-0bc1-4b83-ac2d-d421d6f8ad06%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/3b3fb4ff-0bc1-4b83-ac2d-d421d6f8ad06%40googlegroups.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). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/2dad1568-715a-4b35-91ce-7c5c56692919%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/2dad1568-715a-4b35-91ce-7c5c56692919%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:** [February 10, 2014, 5:20pm UTC](https://discuss.elastic.co/t/performance-question-about-shards-and-replicas/15690/4 "2014-02-10T17:20:21Z")
Your question boils down to "if there is more than one shard per node, does it harm search or index speed"? The answer is, it depends. If you have powerful nodes regarding CPU and RAM and your shards are not too big, you can use more than one shard happily. If you use too many shards per node, you will notice it when you run out of resources. If you plan to use more than two nodes, creating more than 1 shard per index is very welcome so the index can keep up with the node count. 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/CAKdsXoEX6XwFUN6xcm7g4YorQqBYoa44p9DNxXESPkygm-iGyw%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAKdsXoEX6XwFUN6xcm7g4YorQqBYoa44p9DNxXESPkygm-iGyw%40mail.gmail.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![Binh\_Ly](https://avatars.discourse-cdn.com/v4/letter/b/ce7236/32.png) [@Binh\_Ly](https://discuss.elastic.co/u/Binh_Ly)\ **Post date:** [February 10, 2014, 5:48pm UTC](https://discuss.elastic.co/t/performance-question-about-shards-and-replicas/15690/5 "2014-02-10T17:48:45Z")
Just FYI, barring differences in the low-level segments, for all intents and purposes, a primary shard and a corresponding replica shard should be the same in terms of query performance. Jorge is correct, you can think of shards as a horizontal content/resource scaling unit. And replicas as a horizontal query performance and redundancy scaling unit. On Monday, February 10, 2014 11:01:01 AM UTC-5, Valentin wrote: > Thanks. The split brain problem aside: Is it faster for elasticsearch to > read a shard than a replica? -- 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/d49b4187-bcb7-4816-a249-38bf9bc1105d%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/d49b4187-bcb7-4816-a249-38bf9bc1105d%40googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![Valentin\_Pletzer](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/valentin_pletzer/32/105548_2.png) [@Valentin\_Pletzer](https://discuss.elastic.co/u/Valentin_Pletzer)\ **Post date:** [February 10, 2014, 7:23pm UTC](https://discuss.elastic.co/t/performance-question-about-shards-and-replicas/15690/6 "2014-02-10T19:23:48Z")
Thanks for all the answers guys! One final thought: Theoretically, if every node has only one shard and no replicas, each node could only search the data it has and no redudant data. Shouldn't that have an (small) impact on the indexing/searching of the data? -- 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/ff2fcb26-33c7-4d9c-8268-1ea47fda4bbd%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/ff2fcb26-33c7-4d9c-8268-1ea47fda4bbd%40googlegroups.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, 1:51am UTC](https://discuss.elastic.co/t/performance-question-about-shards-and-replicas/15690/7 "2017-07-06T01:51:23Z")