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
```
Alternatively, if Auto-TLS is enabled for the Solr service or the service has complex SSL configurations, use the the following REST API commands for restoring collections.
1. Ensure that the existing collection is removed to prevent the metadata conflicts.
```
solrctl --zk [***ZK_QUORUM***]/solr-infra collection --delete [***COLLECTION_NAME***]
```
2. Execute the restore operation through the Collections API.
```
curl -ivk --negotiate -u : \
"https://[***SOLR_HOST***]:8995/solr/admin/collections?action=RESTORE\
&name=[***BACKUP_NAME***]\
&location=[***BACKUP_LOCATION_PATH***]\
&collection=[***TARGET_COLLECTION_NAME***]"
```
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.