# Which config parameter can make ES 2.1's default write replica action from sync to async?

**URL:** <https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728>\
**Category:** Elasticsearch\
**Created:** [December 22, 2015, 3:41am UTC](https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728 "2015-12-22T03:41:36Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![makeyang](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@makeyang](https://discuss.elastic.co/u/makeyang)\
**Post date:** [December 22, 2015, 3:41am UTC](https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728/1 "2015-12-22T03:41:36Z")

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we don't want to sync write to replica. So we'd like to modified it.

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**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:** [December 22, 2015, 4:53am UTC](https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728/2 "2015-12-22T04:53:25Z")

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You cannot, it is no longer configurable in 2.X.

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**Author:** ![makeyang](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@makeyang](https://discuss.elastic.co/u/makeyang)\
**Post date:** [December 22, 2015, 5:16am UTC](https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728/3 "2015-12-22T05:16:53Z")

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> [@warkolm](#):
>
> You cannot, it is no longer configurable in 2.X.

so the only way to asyn is to let client change it, right?

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**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:** [December 22, 2015, 5:18am UTC](https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728/4 "2015-12-22T05:18:07Z")

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No, you cannot do it. At all.

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**Author:** ![makeyang](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@makeyang](https://discuss.elastic.co/u/makeyang)\
**Post date:** [December 22, 2015, 9:10am UTC](https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728/5 "2015-12-22T09:10:31Z")

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under this situation, when a shard is down, how ES deal with write request? will it wait for recovery then execute write or it will response fail to client before recovery?

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**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:** [December 22, 2015, 10:38am UTC](https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728/6 "2015-12-22T10:38:44Z")

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[Write consistency](https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-index_.html#index-consistency) still applies here, so it depends on how many replicas you have.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 5, 2017, 11:29pm UTC](https://discuss.elastic.co/t/which-config-parameter-can-make-es-2-1s-default-write-replica-action-from-sync-to-async/37728/7 "2017-07-05T23:29:20Z")

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