Briefly, this error occurs when Elasticsearch tries to delete old indices that are no longer in use, but encounters an issue. This could be due to insufficient permissions, disk space issues, or network connectivity problems. To resolve this, you could manually delete the stale indices, ensure that Elasticsearch has the necessary permissions, check for sufficient disk space, or troubleshoot any network issues. Additionally, you could also check the Elasticsearch logs for more detailed information about the error.
This guide will help you check for common problems that cause the log ” [{}] Exception during cleanup of stale indices ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: indices, repositories, blobstore.
Overview
An Elasticsearch snapshot provides a backup mechanism that takes the current state and data in the cluster and saves it to a repository (read snapshot for more information). The backup process requires a repository to be created first. The repository needs to be registered using the _snapshot endpoint, and multiple repositories can be created per cluster. The following repository types are supported:
Repository types
| Repository type | Configuration type |
|---|---|
| Shared file system | Type: “fs” |
| S3 | Type : “s3” |
| HDFS | Type :“hdfs” |
| Azure | Type: “azure” |
| Google Cloud Storage | Type : “gcs” |
Examples
To register an “fs” repository:
PUT _snapshot/my_repo_01
{
"type": "fs",
"settings": {
"location": "/mnt/my_repo_dir"
}
}Notes and good things to know
- S3, HDFS, Azure and Google Cloud require a relevant plugin to be installed before it can be used for a snapshot.
- The setting, path.repo: /mnt/my_repo_dir needs to be added to elasticsearch.yml on all the nodes if you are planning to use the repo type of file system. Otherwise, it will fail.
- When using remote repositories, the network bandwidth and repository storage throughput should be high enough to complete the snapshot operations normally, otherwise you will end up with partial snapshots.
Log Context
Log “[{}] Exception during cleanup of stale indices” classname is BlobStoreRepository.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
} catch (Exception e) {
// TODO: We shouldn't be blanket catching and suppressing all exceptions here and instead handle them safely upstream.
// Currently this catch exists as a stop gap solution to tackle unexpected runtime exceptions from implementations
// bubbling up and breaking the snapshot functionality.
assert false : e;
logger.warn(new ParameterizedMessage("[{}] Exception during cleanup of stale indices"; metadata.name()); e);
}
return deleteResult;
}
@Override
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