OpenSearch Cluster Status Red

How to fix it

// try these in order, the most common fix is first

1. FIX 1Find the red index

   Copy steps
   1. 01Run GET _cluster/health?pretty
   2. 02Run GET _cat/indices?v&health=red
   3. 03Run GET _cluster/allocation/explain to see why the first unassigned shard cannot be placed
   Did this fix it? Yes No

2. FIX 2Fix the underlying cause

   Copy steps
   1. 01Bring failed nodes back or add nodes
   2. 02Free disk space or add storage if watermarks are hit
   3. 03Check JVM memory pressure and CPU, then scale or reduce load
   Did this fix it? Yes No

3. FIX 3Retry allocation

   Copy steps
   1. 01Run POST _cluster/reroute?retry_failed=true
   2. 02Confirm allocation is enabled: GET _cluster/settings
   Did this fix it? Yes No

4. FIX 4Restore or delete as last resort

   Copy steps
   1. 01Restore the index from a snapshot
   2. 02On Amazon's service deleting the red index is the quickest route but loses its data; do it only if you can recreate it
   3. 03Fix red status before reconfiguring a managed domain, otherwise it can stick in Processing
   Did this fix it? Yes No

Symptoms

Cluster health shows red, some searches or writes fail, and automated snapshots fail while red persists.

Why it happens

• C-01A data node failed or restarted
• C-02Disk full or watermark exceeded
• C-03Continuous heavy load or heap exhaustion crashing nodes
• C-04No replica for the affected index
• C-05Shard allocation disabled or filtered by settings

// this guide also covers

• opensearch cluster red
• opensearch red status
• opensearch unassigned shards
• opensearch cluster health red

Other OpenSearch errors

• OpenSearch Cluster Status Yellow
• OpenSearch Unassigned Shards
• OpenSearch High JVM Memory Pressure
• OpenSearch OutOfMemoryError and Circuit Breaker
• OpenSearch Exceeded Maximum Shard Limit
• OpenSearch Index Read-Only: Disk Watermark and ClusterBlockException
• OpenSearch 429 Too Many Requests
• OpenSearch Docker Container Won't Start