# Difficult to tame cluster **URL:** \ **Category:** Elasticsearch\ **Created:** [April 13, 2015, 4:03pm UTC](https://discuss.elastic.co/t/difficult-to-tame-cluster/23213 "2015-04-13T16:03:20Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Debayan\_Banerjee](https://avatars.discourse-cdn.com/v4/letter/d/58f4c7/32.png) [@Debayan\_Banerjee](https://discuss.elastic.co/u/Debayan_Banerjee)\ **Post date:** [April 13, 2015, 4:03pm UTC](https://discuss.elastic.co/t/difficult-to-tame-cluster/23213/1 "2015-04-13T16:03:20Z")
Hi, We are having a hard time trying to keep our 4 node cluster (ES 1.4.4) up with high indexing load. I have noticed that one of the nodes, which only has replica shards, does no indexing at all (no blue lines in paramedic UI). Is it true that replica shards do not indexing of data? Do they simply copy the indices from primary shards? If that is the case, I am planning to keep a machine with replica shards only behind production LB to keep serving read requests even if the original primary shards machine goes down. -- Debayan Banerjee -- 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/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**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:** [April 15, 2015, 5:29am UTC](https://discuss.elastic.co/t/difficult-to-tame-cluster/23213/2 "2015-04-15T05:29:41Z")
Yes, replicas only receive data (and searches), they do no indexing. On 14 April 2015 at 02:03, Debayan Banerjee [debayan.banerjee@paytm.com](mailto:debayan.banerjee@paytm.com) wrote: > Hi, > > We are having a hard time trying to keep our 4 node cluster (ES 1.4.4) up > with high indexing load. I have noticed that one of the nodes, which only > has replica shards, does no indexing at all (no blue lines in paramedic > UI). > > Is it true that replica shards do not indexing of data? Do they simply > copy the indices from primary shards? If that is the case, I am planning to > keep a machine with replica shards only behind production LB to keep > serving read requests even if the original primary shards machine goes down. > > -- > > Debayan Banerjee > > -- > 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/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com) > [https://groups.google.com/d/msgid/elasticsearch/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com?utm_medium=email&utm_source=footer) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- 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/CAEYi1X\_gRFdX7VnNZUQQwYEbPRE7G%3DNh8g%2BJpr7drsZ7w\_j32g%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAEYi1X_gRFdX7VnNZUQQwYEbPRE7G%3DNh8g%2BJpr7drsZ7w_j32g%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![Debayan\_Banerjee](https://avatars.discourse-cdn.com/v4/letter/d/58f4c7/32.png) [@Debayan\_Banerjee](https://discuss.elastic.co/u/Debayan_Banerjee)\ **Post date:** [April 16, 2015, 6:19am UTC](https://discuss.elastic.co/t/difficult-to-tame-cluster/23213/3 "2015-04-16T06:19:10Z")
I have been able to solve this. We were previously using 4 dual core machines. I have now resorted to using 2 quad core machines instead. On these machines, I have limited index and bulk threadpool sizes to 1 each. This ensures that even in heavy workload 2 cores are free for search threadpool and other OS related functions. This has been working well. On Wed, Apr 15, 2015 at 10:59 AM, Mark Walkom [markwalkom@gmail.com](mailto:markwalkom@gmail.com) wrote: > Yes, replicas only receive data (and searches), they do no indexing. > > On 14 April 2015 at 02:03, Debayan Banerjee [debayan.banerjee@paytm.com](mailto:debayan.banerjee@paytm.com) > wrote: > > > Hi, > > > > We are having a hard time trying to keep our 4 node cluster (ES 1.4.4) up > > with high indexing load. I have noticed that one of the nodes, which only > > has replica shards, does no indexing at all (no blue lines in paramedic > > UI). > > > > Is it true that replica shards do not indexing of data? Do they simply > > copy the indices from primary shards? If that is the case, I am planning to > > keep a machine with replica shards only behind production LB to keep > > serving read requests even if the original primary shards machine goes down. > > > > -- > > > > Debayan Banerjee > > > > -- > > 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/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com) > > [https://groups.google.com/d/msgid/elasticsearch/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/CAOvawCs%3Deb89K7MuyeR0UQvkoW7Ys19t17eFWi-vWs5R9nGpDw%40mail.gmail.com?utm_medium=email&utm_source=footer) > > . > > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). > > -- > 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/CAEYi1X\_gRFdX7VnNZUQQwYEbPRE7G%3DNh8g%2BJpr7drsZ7w\_j32g%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAEYi1X_gRFdX7VnNZUQQwYEbPRE7G%3DNh8g%2BJpr7drsZ7w_j32g%40mail.gmail.com) > [https://groups.google.com/d/msgid/elasticsearch/CAEYi1X\_gRFdX7VnNZUQQwYEbPRE7G%3DNh8g%2BJpr7drsZ7w\_j32g%40mail.gmail.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/CAEYi1X_gRFdX7VnNZUQQwYEbPRE7G%3DNh8g%2BJpr7drsZ7w_j32g%40mail.gmail.com?utm_medium=email&utm_source=footer) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- Debayan Banerjee devOps engineer +91 8800846550 -- 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/CAOvawCtqmqFgoCQ6-1CDE\_-4zJ-mrcq8vasJowSY4R2Udb9QHw%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAOvawCtqmqFgoCQ6-1CDE_-4zJ-mrcq8vasJowSY4R2Udb9QHw%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**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, 12:19am UTC](https://discuss.elastic.co/t/difficult-to-tame-cluster/23213/4 "2017-07-06T00:19:23Z")