Briefly, this error occurs when Elasticsearch tries to delete snapshots that do not exist in the specified repository. This could be due to a miscommunication or a synchronization issue between nodes. To resolve this, you can first verify the existence of the snapshot by using the GET snapshot API. If the snapshot doesn’t exist, you can ignore the error. If it does exist, try to delete it again. If the error persists, check the health of your nodes and ensure they are properly synchronized.
This guide will help you check for common problems that cause the log ” Attempting to remove non-existent snapshots {} from repository data ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: 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 “Attempting to remove non-existent snapshots {} from repository data” class name is RepositoryData.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
.filter(Predicate.not(snapshots::contains))
.collect(Collectors.toMap(SnapshotId::getUUID; Function.identity()));
if (newSnapshotIds.size() != snapshotIds.size() - snapshots.size()) {
final Collection notFound = new HashSet<>(snapshots);
notFound.removeAll(snapshotIds.values());
throw new ResourceNotFoundException("Attempting to remove non-existent snapshots {} from repository data"; notFound);
}
final Map newSnapshotsDetails = new HashMap<>(snapshotsDetails);
for (SnapshotId snapshotId : snapshots) {
newSnapshotsDetails.remove(snapshotId.getUUID());
}
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