# Update minimum\_master\_nodes? **URL:** \ **Category:** Elasticsearch\ **Created:** [August 17, 2011, 8:48am UTC](https://discuss.elastic.co/t/update-minimum-master-nodes/5182 "2011-08-17T08:48:43Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Lukas\_Vlcek1](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lukas_vlcek1/32/819_2.png) [@Lukas\_Vlcek1](https://discuss.elastic.co/u/Lukas_Vlcek1)\ **Post date:** [August 17, 2011, 8:48am UTC](https://discuss.elastic.co/t/update-minimum-master-nodes/5182/1 "2011-08-17T08:48:43Z")
Hi, is it possible to update minimum\_master\_nodes value via Update API? I am thinking of the following cluster upgrade scenario: Let's say I have a 3 node cluster (in this case the minimum\_master\_nodes should be set probably to 2). If there are 3 nodes I think it is possible to do an upgrade of search service without downtime. For example if I need to upgrade to a new version of ES or I need to do a significant update to mappings I can simply take one node out of that 3 node cluster, upgrade it, re-index data into it if needed, take another node from the 2 node cluster, upgrade it as well and have it form a new cluster with the newly upgraded node and have data replicated. Redirect clients to the new cluster, shutdown the last remaining node from the original cluster, upgrade it and have it join the new cluster. Given that the network traffic from clients won't be high such upgrade strategy should be possible (hopefully?). But the problem is that if the minimum\_master\_nodes can not be updated then it is not possible to do such upgrade (the other option would be to set the master number value to 1). Regards, Lukas ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [August 17, 2011, 11:43am UTC](https://discuss.elastic.co/t/update-minimum-master-nodes/5182/2 "2011-08-17T11:43:38Z")
You can't update the settings in realtime. There are two aspects of elasticsearch that are missing in terms of realtime updates of settings. They are cluster wide settings and node level settings. Both should be provided. On Wed, Aug 17, 2011 at 11:48 AM, Lukáš Vlček [lukas.vlcek@gmail.com](mailto:lukas.vlcek@gmail.com) wrote: > Hi, > > is it possible to update minimum\_master\_nodes value via Update API? > I am thinking of the following cluster upgrade scenario: > Let's say I have a 3 node cluster (in this case the minimum\_master\_nodes > should be set probably to 2). If there are 3 nodes I think it is possible to > do an upgrade of search service without downtime. For example if I need to > upgrade to a new version of ES or I need to do a significant update to > mappings I can simply take one node out of that 3 node cluster, upgrade it, > re-index data into it if needed, take another node from the 2 node cluster, > upgrade it as well and have it form a new cluster with the newly upgraded > node and have data replicated. Redirect clients to the new cluster, shutdown > the last remaining node from the original cluster, upgrade it and have it > join the new cluster. Given that the network traffic from clients won't be > high such upgrade strategy should be possible (hopefully?). But the problem > is that if the minimum\_master\_nodes can not be updated then it is not > possible to do such upgrade (the other option would be to set the master > number value to 1). > > Regards, > Lukas ---
**Author:** ![Lukas\_Vlcek1](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lukas_vlcek1/32/819_2.png) [@Lukas\_Vlcek1](https://discuss.elastic.co/u/Lukas_Vlcek1)\ **Post date:** [August 17, 2011, 12:10pm UTC](https://discuss.elastic.co/t/update-minimum-master-nodes/5182/3 "2011-08-17T12:10:11Z")
OK, looking forward to the next releases with optimism 🙂 I can live without it for now, I will just go with minimum master nodes = 1 and cross my fingers to not experience split brains. Would there be any recommendation regarding the upgrade process that I described? Is it a good idea and are there any settings that I should pay attention to in this case? Regards, Lukas On Wed, Aug 17, 2011 at 1:43 PM, Shay Banon [kimchy@gmail.com](mailto:kimchy@gmail.com) wrote: > You can't update the settings in realtime. There are two aspects of > elasticsearch that are missing in terms of realtime updates of settings. > They are cluster wide settings and node level settings. Both should be > provided. > > On Wed, Aug 17, 2011 at 11:48 AM, Lukáš Vlček [lukas.vlcek@gmail.com](mailto:lukas.vlcek@gmail.com)wrote: > > > Hi, > > > > is it possible to update minimum\_master\_nodes value via Update API? > > I am thinking of the following cluster upgrade scenario: > > Let's say I have a 3 node cluster (in this case the minimum\_master\_nodes > > should be set probably to 2). If there are 3 nodes I think it is possible to > > do an upgrade of search service without downtime. For example if I need to > > upgrade to a new version of ES or I need to do a significant update to > > mappings I can simply take one node out of that 3 node cluster, upgrade it, > > re-index data into it if needed, take another node from the 2 node cluster, > > upgrade it as well and have it form a new cluster with the newly upgraded > > node and have data replicated. Redirect clients to the new cluster, shutdown > > the last remaining node from the original cluster, upgrade it and have it > > join the new cluster. Given that the network traffic from clients won't be > > high such upgrade strategy should be possible (hopefully?). But the problem > > is that if the minimum\_master\_nodes can not be updated then it is not > > possible to do such upgrade (the other option would be to set the master > > number value to 1). > > > > Regards, > > Lukas ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [August 18, 2011, 12:07pm UTC](https://discuss.elastic.co/t/update-minimum-master-nodes/5182/4 "2011-08-18T12:07:16Z")
The upgrade proces is different if you want to reindex data compared to upgrading a version. If you need to reindex data, then you can use an existing cluster and reindex into a new index / indices. Then, you can use aliases to switch to the "new version". Regarding upgrading elasticsearch versions, if its a minor version, you can do a rolling restart. If its a major version, then you need to do a full restart. Note, sometimes, it just make sense to do a full restart as it requires less data to be moved around. There is an issue open to try and address rebalancing when doing rolling restart, though tricky 🙂 On Wed, Aug 17, 2011 at 3:10 PM, Lukáš Vlček [lukas.vlcek@gmail.com](mailto:lukas.vlcek@gmail.com) wrote: > OK, looking forward to the next releases with optimism 🙂 > > I can live without it for now, I will just go with minimum master nodes = 1 > and cross my fingers to not experience split brains. Would there be any > recommendation regarding the upgrade process that I described? Is it a good > idea and are there any settings that I should pay attention to in this case? > > Regards, > Lukas > > On Wed, Aug 17, 2011 at 1:43 PM, Shay Banon [kimchy@gmail.com](mailto:kimchy@gmail.com) wrote: > > > You can't update the settings in realtime. There are two aspects of > > elasticsearch that are missing in terms of realtime updates of settings. > > They are cluster wide settings and node level settings. Both should be > > provided. > > > > On Wed, Aug 17, 2011 at 11:48 AM, Lukáš Vlček [lukas.vlcek@gmail.com](mailto:lukas.vlcek@gmail.com)wrote: > > > > > Hi, > > > > > > is it possible to update minimum\_master\_nodes value via Update API? > > > I am thinking of the following cluster upgrade scenario: > > > Let's say I have a 3 node cluster (in this case the minimum\_master\_nodes > > > should be set probably to 2). If there are 3 nodes I think it is possible to > > > do an upgrade of search service without downtime. For example if I need to > > > upgrade to a new version of ES or I need to do a significant update to > > > mappings I can simply take one node out of that 3 node cluster, upgrade it, > > > re-index data into it if needed, take another node from the 2 node cluster, > > > upgrade it as well and have it form a new cluster with the newly upgraded > > > node and have data replicated. Redirect clients to the new cluster, shutdown > > > the last remaining node from the original cluster, upgrade it and have it > > > join the new cluster. Given that the network traffic from clients won't be > > > high such upgrade strategy should be possible (hopefully?). But the problem > > > is that if the minimum\_master\_nodes can not be updated then it is not > > > possible to do such upgrade (the other option would be to set the master > > > number value to 1). > > > > > > Regards, > > > Lukas ---
**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, 3:56am UTC](https://discuss.elastic.co/t/update-minimum-master-nodes/5182/5 "2017-07-06T03:56:43Z")