# Replication single threaded? **URL:** \ **Category:** Elasticsearch\ **Created:** [September 14, 2013, 9:25am UTC](https://discuss.elastic.co/t/replication-single-threaded/13604 "2013-09-14T09:25:30Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Alexis\_Okuwa](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/alexis_okuwa/32/1983_2.png) [@Alexis\_Okuwa](https://discuss.elastic.co/u/Alexis_Okuwa)\ **Post date:** [September 14, 2013, 9:25am UTC](https://discuss.elastic.co/t/replication-single-threaded/13604/1 "2013-09-14T09:25:30Z")
I started to test adding and removing nodes from my cluster and testing the performance but I am seeing a lot of the time while the inital data sync is single threaded. Most of the time i see 1 core at 100% and every now and then the other cores are getting some usage but its clear that 1 core is working 3 to 4 times harder then the other cores? -- 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:** ![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:** [September 14, 2013, 12:12pm UTC](https://discuss.elastic.co/t/replication-single-threaded/13604/2 "2013-09-14T12:12:33Z")
There is no single threaded data sync. What you see is index recovery, downloading shards from the gateway. You can modify the recovery settings in configuration to minimize the recovery phases, by default, recovery is placed in the background so it does not disturb ongoing saerch/index so much. 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). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![Alexis\_Okuwa](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/alexis_okuwa/32/1983_2.png) [@Alexis\_Okuwa](https://discuss.elastic.co/u/Alexis_Okuwa)\ **Post date:** [September 14, 2013, 12:18pm UTC](https://discuss.elastic.co/t/replication-single-threaded/13604/3 "2013-09-14T12:18:52Z")
is the recovery also occured when its not a recovery like when its a clean node? On Sat, Sep 14, 2013 at 5:12 AM, [joergprante@gmail.com](mailto:joergprante@gmail.com) \< [joergprante@gmail.com](mailto:joergprante@gmail.com)\> wrote: > There is no single threaded data sync. What you see is index recovery, > downloading shards from the gateway. You can modify the recovery settings > in configuration to minimize the recovery phases, by default, recovery is > placed in the background so it does not disturb ongoing saerch/index so > much. > > Jörg > > -- > You received this message because you are subscribed to a topic in the > Google Groups "elasticsearch" group. > To unsubscribe from this topic, visit > [https://groups.google.com/d/topic/elasticsearch/NoTTQoKAvpE/unsubscribe](https://groups.google.com/d/topic/elasticsearch/NoTTQoKAvpE/unsubscribe). > To unsubscribe from this group and all its topics, 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). -- Enjoy, Alexis Okuwa WojonsTech 424.835.1223 -- 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:** ![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:** [September 14, 2013, 12:26pm UTC](https://discuss.elastic.co/t/replication-single-threaded/13604/4 "2013-09-14T12:26:20Z")
Recovery is not per node, but per index. If a node starts up, it receives messages what shards it shall house. Then, these shards are either activated if locally present, or the shard is received from another node. If an index is complete over all shards, the recovery of the index is complete. 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). 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, 2:16am UTC](https://discuss.elastic.co/t/replication-single-threaded/13604/5 "2017-07-06T02:16:31Z")
Closed on July 6, 2017, 2:16am UTC