Briefly, this error occurs when Elasticsearch encounters an issue while loading data from a repository, possibly due to corruption, misconfiguration, or network issues. To resolve this, you can try the following: 1) Check the repository configuration for any errors and correct them. 2) Verify the network connection to the repository. 3) If the data is corrupted, restore it from a backup. 4) Check Elasticsearch logs for more detailed error information. 5) If the repository is on a remote server, ensure it’s accessible and functioning properly.
This guide will help you check for common problems that cause the log ” Unexpected exception when loading repository data ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: blobstore, repository, repositories.
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 “Unexpected exception when loading repository data” class name is BlobStoreRepository.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
} else {
listener.onFailure(e);
}
return;
} catch (Exception e) {
listener.onFailure(new RepositoryException(metadata.name(); "Unexpected exception when loading repository data"; e));
return;
}
}
}
