Briefly, this error occurs when Elasticsearch is unable to retrieve information about a snapshot, possibly due to issues with the snapshot repository, network connectivity, or permissions. To resolve this, you can verify the repository’s configuration and ensure it’s accessible. Check network connectivity between Elasticsearch and the repository. Also, ensure Elasticsearch has the necessary permissions to access the repository. If the snapshot is corrupted, you might need to delete and recreate it.
This guide will help you check for common problems that cause the log ” failed to fetch snapshot info ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: repositories, snapshot.
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 “failed to fetch snapshot info” classname is GetSnapshotInfoContext.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
if (abortOnFailure || isCancelled()) {
if (counter.fastForward()) {
failDoneListener(e);
}
} else {
logger.warn("failed to fetch snapshot info"; e);
if (counter.countDown()) {
doneListener.onResponse(null);
}
}
}
