How to fix SnapshotException: [repository:snapshot] Snapshot could not be read in Elasticsearch

# Test repository connectivity
curl -X GET "localhost:9200/_snapshot/my_repository" -u "username:password"

# Get repository details
curl -X GET "localhost:9200/_snapshot/my_repository/_all" -u "username:password"

# For filesystem repositories, check permissions
ls -la /path/to/repository/
# Ensure Elasticsearch user has read access to all files

# For S3/GCS/Azure repositories, check credentials and network connectivity
curl -X POST "localhost:9200/_snapshot/my_repository/_verify" -u "username:password"

# Get detailed snapshot information
curl -X GET "localhost:9200/_snapshot/my_repository/snapshot_name?verbose=true" -u "username:password"

# Look for these key fields in the response:
# - "state": Should be "SUCCESS" for valid snapshots
# - "failures": Any failures during snapshot creation
# - "shards": Check for failed shards

# List all snapshots in repository to see which are readable
curl -X GET "localhost:9200/_snapshot/my_repository/_all" -u "username:password"

# For filesystem repositories, manually check metadata files
ls -la /path/to/repository/indices/
# Look for missing .dat or .meta files

# 1. Delete and recreate the repository (CAUTION: This deletes ALL snapshots!)
# Only do this if you have backups elsewhere
curl -X DELETE "localhost:9200/_snapshot/my_repository" -u "username:password"
curl -X PUT "localhost:9200/_snapshot/my_repository" -u "username:password" -H 'Content-Type: application/json' -d'
{
  "type": "fs",
  "settings": {
    "location": "/path/to/repository",
    "compress": true
  }
}
'

# 2. For S3/GCS/Azure repositories, check if you can access files directly
# Use cloud provider tools to verify file existence and integrity

# 3. If you have multiple snapshots, identify which ones are corrupted
# and delete only the problematic ones:
curl -X DELETE "localhost:9200/_snapshot/my_repository/corrupted_snapshot" -u "username:password"

# 4. Create a new snapshot from healthy indices
curl -X PUT "localhost:9200/_snapshot/my_repository/new_snapshot?wait_for_completion=true" -u "username:password" -H 'Content-Type: application/json' -d'
{
  "indices": "index1,index2",
  "ignore_unavailable": true,
  "include_global_state": false
}
'

# 1. Check for other available snapshots
curl -X GET "localhost:9200/_snapshot/my_repository/_all" -u "username:password"

# 2. Restore from a different snapshot
curl -X POST "localhost:9200/_snapshot/my_repository/alternative_snapshot/_restore?wait_for_completion=true" -u "username:password" -H 'Content-Type: application/json' -d'
{
  "indices": "index1,index2",
  "ignore_unavailable": true,
  "include_global_state": false,
  "include_aliases": false,
  "rename_pattern": "(.+)",
  "rename_replacement": "restored_$1"
}
'

# 3. Partial restore if only some indices are corrupted
# List indices in the corrupted snapshot first:
curl -X GET "localhost:9200/_snapshot/my_repository/corrupted_snapshot" -u "username:password"
# Then restore only healthy indices

# 4. Cross-cluster restore from another repository
# If you have the same snapshot in a different repository:
curl -X POST "localhost:9200/_snapshot/other_repository/same_snapshot/_restore" -u "username:password"

# 1. Regular snapshot verification
curl -X POST "localhost:9200/_snapshot/my_repository/_verify" -u "username:password"

# 2. Implement snapshot lifecycle management (SLM)
curl -X PUT "localhost:9200/_slm/policy/daily-backups" -u "username:password" -H 'Content-Type: application/json' -d'
{
  "schedule": "0 30 1 * * ?",
  "name": "<daily-snap-{now/d}>",
  "repository": "my_repository",
  "config": {
    "indices": ["*"],
    "ignore_unavailable": false,
    "include_global_state": false
  },
  "retention": {
    "expire_after": "30d",
    "min_count": 5,
    "max_count": 50
  }
}
'

# 3. Monitor snapshot health
curl -X GET "localhost:9200/_slm/stats" -u "username:password"
curl -X GET "localhost:9200/_snapshot/my_repository/_status" -u "username:password"

# 4. Regular repository maintenance
# For filesystem repositories:
df -h /path/to/repository  # Check disk space