elasticsearch/docs/reference/troubleshooting/fix-common-cluster-issues.asciidoc
Iraklis Psaroudakis 34471b1cd2
Introduce max headroom for disk watermark stages (#88639)
Introduce max headroom settings for the low, high, and flood disk watermark stages, similar to the existing max headroom setting for the flood stage of the frozen tier. Introduce new max headrooms in HealthMetadata and in ReactiveStorageDeciderService. Add multiple tests in DiskThresholdDeciderUnitTests, DiskThresholdDeciderTests and DiskThresholdMonitorTests. Moreover, addition & subtraction for ByteSizeValue, and min.
2022-09-19 14:59:18 +03:00

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[[fix-common-cluster-issues]]
== Fix common cluster issues
This guide describes how to fix common errors and problems with {es} clusters.
<<disk-usage-exceeded,Error: disk usage exceeded flood-stage watermark, index has read-only-allow-delete block>>::
This error indicates a data node is critically low on disk space and has reached
the flood-stage disk usage watermark.
<<circuit-breaker-errors,Circuit breaker errors>>::
{es} uses circuit breakers to prevent nodes from running out of JVM heap memory.
If Elasticsearch estimates an operation would exceed a circuit breaker, it stops
the operation and returns an error.
<<high-cpu-usage,High CPU usage>>::
The most common causes of high CPU usage and their solutions.
<<high-jvm-memory-pressure,High JVM memory pressure>>::
High JVM memory usage can degrade cluster performance and trigger circuit
breaker errors.
<<red-yellow-cluster-status,Red or yellow cluster status>>::
A red or yellow cluster status indicates one or more shards are missing or
unallocated. These unassigned shards increase your risk of data loss and can
degrade cluster performance.
<<rejected-requests,Rejected requests>>::
When {es} rejects a request, it stops the operation and returns an error with a
`429` response code.
<<task-queue-backlog,Task queue backlog>>::
A backlogged task queue can prevent tasks from completing and put the cluster
into an unhealthy state.
<<diagnose-unassigned-shards,Diagnose unassigned shards>>::
There are multiple reasons why shards might get unassigned, ranging from
misconfigured allocation settings to lack of disk space.
<<cluster-fault-detection-troubleshooting,Troubleshooting an unstable cluster>>::
A cluster in which nodes leave unexpectedly is unstable and can create several
issues.
include::common-issues/disk-usage-exceeded.asciidoc[]
include::common-issues/circuit-breaker-errors.asciidoc[]
include::common-issues/high-cpu-usage.asciidoc[]
include::common-issues/high-jvm-memory-pressure.asciidoc[]
include::common-issues/red-yellow-cluster-status.asciidoc[]
include::common-issues/rejected-requests.asciidoc[]
include::common-issues/task-queue-backlog.asciidoc[]
include::common-issues/diagnose-unassigned-shards.asciidoc[]