I'm curious how it is possible that a cluster on Elastic Cloud passes the memory lock bootstrap check even though the memory doesn't seem to be locked. Here is the mlockall state on all nodes GET _nodes?filter_path=**.mlockall { "nodes" : { "9jimFRh_SpCU6zWrdzb2cA" : { "process" : { …

The recommendation is to disable swap entirely : There are three approaches to disabling swapping. The preferred option is to completely disable swap. If this is not an option, whether or not to prefer minimizing swappiness versus memory locking is dependent on your environment. bootstrap.memory_…

[image] val: Is it because swappiness and/or swapoff is/are enough? No, it's because memory locking is disabled. From the docs you linked: The memory lock check verifies that if the bootstrap.memory_lock setting is enabled, that the JVM was successfully able to lock the heap. Since boots…

Thank you David. What I don't understand is how it is possible that a production cluster on Elastic Cloud can start even though the memory lock bootstrap check is not satisfied? According to the bootstrap checks description: If Elasticsearch is in production mode, any bootstrap checks that fail…

Maybe it helps to look at the source code? elastic/elasticsearch/blob/780f27306777399db574b9f9a9f44e77f41779f3/server/src/main/java/org/elasticsearch/bootstrap/BootstrapChecks.java#L309-L313 if (BootstrapSettings.MEMORY_LOCK_SETTING.get(context.settings()) && isMemoryLocked() == false) { …

You're right, I could have checked the source code first. Thanks for the insights!

Ok, so that means on Elastic Cloud, this is done at the OS-level using swapoff and it's not necessarily apparent in the cluster/node configuration. That makes perfect sense then. Thank you so much!!

Memory lock check on Elastic Cloud

Elastic Stack Elasticsearch

val (Val Crettaz) February 23, 2021, 5:07am 6

@DavidTurner Maybe you can shed some more light on why it is recommended to lock memory and Elastic Cloud doesn't?

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Memory lock check on Elastic Cloud

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