Briefly, this error occurs when Elasticsearch encounters issues while trying to clean up root level blobs, which are typically used for storing snapshots. This could be due to insufficient permissions, disk space issues, or network connectivity problems with the blob storage. To resolve this, you can check and adjust the permissions, ensure there’s enough disk space, and verify the network connectivity. Also, check the health of your blob storage and ensure it’s functioning properly. If the issue persists, consider reconfiguring your snapshot settings or consult with your storage provider.
This guide will help you check for common problems that cause the log ” [{}] Exception during cleanup of root level blobs ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: 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 root level blobs” 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 root level blobs"; metadata.name()); e);
}
return Collections.emptyList();
}
private DeleteResult cleanupStaleIndices(Map foundIndices; Set survivingIndexIds) {
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