Restoring a collection

You can restore a Solr collection from a backup stored on either a remote cluster or the local cluster using the solrctl utility. You must pass a unique request identifier as part of the restore command in the solrctl utility while initiating the restore operation for tracking the process.

If you are using a secure (Kerberos-enabled) cluster, specify your jaas.conf file by adding the following parameter to each command:

-jaas [***/PATH/TO/JAAS.CONF***]

If TLS is enabled for the Solr service, specify the truststore and password by using the ZKCLI_JVM_FLAGS environment variable before you begin the procedure:

export ZKCLI_JVM_FLAGS="-Djavax.net.ssl.trustStore=[***/PATH/TO/TRUSTSTORE \
-Djavax.net.ssl.trustStorePassword=[***TRUST_STORE_PASSWORD***]"

If you are restoring from a backup stored on a remote cluster, copy the backup from the remote cluster to the local cluster. If you are restoring from a local backup, skip this step.
Run the following commands on the cluster to which you want to restore the collection:
```
hdfs dfs -mkdir -p [***PATH/TO/RESTORE/STAGING***]hadoop distcp [***PROTOCOL***]://[***NAMENODE***]:[***PORT***]/[***PATH/TO/BACKUP***] [***/PATH/TO/RESTORE-STAGING***]
```
For example:
- HDFS
- webHDFS
HDFS protocol:
hadoop distcp hdfs://nn01.example.com:8020/path/to/backups/tweets-202103281043 /path/to/restore-staging
WebHDFS protocol:
hadoop distcp webhdfs://nn01.example.com:20101/path/to/backups/tweets-202103281043 /path/to/restore-staging
Start the restore procedure. Run the following command:
```
solrctl collection --restore [***NAME_OF_THE_RESTORED_COLLECTION***] -l [***BACKUP_LOCATION***] -b [***NAME_OF_THE_SNAPSHOT_TO_BE_RESTORED***] -i [***REQUEST_ID***]
```
Make sure that you use a unique [***REQUEST_ID***] each time you run this command.

note

Statuses of historic job runs are stored in ZooKeeper and can be retrieved using the solrctl collection --request-status [***REQUEST_ID***] command. The number of async call responses stored in a cluster is limited to 10,000.

Status information can be removed from ZooKeeper using the DELETESTATUS API call.
For example:
```
solrctl collection --restore tweets -l /path/to/restore-staging -b tweets-202103281043 -i restore-tweets
```
Monitor the status of the restore operation. Run the following command periodically:
```
solrctl collection --request-status [***REQUEST_ID***]
```
Look for <str name="state"> in the output. For example (emphasis added):
```
solrctl collection --request-status restore-tweets
 <?xml version="1.0" encoding="UTF-8"?> <response> <lst name="responseHeader"> <int name="status"> 0</int> <int name="QTime"> 1</int> </lst> \
<lst name="status"> <str name="state"> completed</str> <str name="msg"> found restore-tweets in completed tasks</str> </lst> </response>
```
The state parameter can be one of the following:
- running: The restore operation is running.
- completed: The restore operation is complete.
- failed: The restore operation failed.
- notfound: The specified [***REQUEST_ID***] does not exist.