Briefly, this error occurs when Elasticsearch is unable to delete specific data, possibly due to insufficient permissions, incorrect index name, or the data is currently in use. To resolve this, ensure you have the correct permissions to delete data. Check if the index name is correct and the data is not being used by any ongoing processes. If the data is locked, try unlocking or closing the index before deletion. Also, ensure the Elasticsearch cluster is in a healthy state.
This guide will help you check for common problems that cause the log ” cannot delete test data at ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: blobstore, delete, repositories.
Overview
DELETE is an Elasticsearch API which removes a document from a specific index. This API requires an index name and _id document to delete the document.
Delete a document
DELETE /my_index/_doc/1
Notes
- A delete request throws 404 error code if the document does not already exist in the index.
- If you want to delete a set of documents that matches a query, you need to use delete by query API.
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 “cannot delete test data at” class name is BlobStoreRepository.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
if (isReadOnly() == false) {
try {
final String testPrefix = testBlobPrefix(seed);
blobStore().blobContainer(basePath().add(testPrefix)).delete();
} catch (Exception exp) {
throw new RepositoryVerificationException(metadata.name(); "cannot delete test data at " + basePath(); exp);
}
}
} // Tracks the latest known repository generation in a best-effort way to detect inconsistent listing of root level index-N blobs
