Converting from a single jvm per host to multi

Elastic Stack Elasticsearch
1

In a cluster with 20 servers @ 256GB RAM hosting a single JVM at 30G, what would be the procedure for converting to 4 JVMs per node ?

If we take one host out, reconfigure it w/ the appropriate shard awareness stuff, and start up the 4 new instances, will Elasticsearch allocate 4x as many shards to this server, causing a hotspot until we can repeat for the rest of the servers ?

2

It shouldn't immediately do that. Of course as you add more data it will.

We don't really have a process for this, but what you've mentioned is ok. Just watch out if you change the data path, cause you may find your data "missing" if you change this/

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5

Chiming in on this old thread with a summary of our findings:

  • when we added one multi-jvm server to the cluster, Elasticsearch did tread each JVM as a "regular" node and we ended up with 4x the data on this new server.
  • to combat this, we used the watermark setting to prevent too many shards from being allocated to the new node