Restore a MongoDB Logical Backup

In this article, we explain how to restore a MongoDB logical backup performed via mongodump to a mongod instance.

MongoDB logical backups require the mongorestore tool to restore data. This article focuses on that process.

Note: Percona provides mongodb_consistent_backup, which wraps mongodump to provide cluster-wide consistency. Backups created with it can be restored using the same steps as standard mongodump backups.

Mongorestore Command Flags

–host / –port (–user / –password)

Required, even for localhost. Include authentication flags if enabled.

–drop

Almost always required. Drops collections before restoring to avoid duplicate key errors.

–oplogReplay

Almost always required. Replays oplog entries for consistency. Look for oplog.bson in the dump directory.

–dir

Required. Path to the mongodump data.

–gzip

Optional. Required if the backup used compression (.bson.gz files).

–numParallelCollections=<number>

Optional. Controls parallelism for restoring collections. Default is 4 threads.

Steps

1. (Optional) Extract the backup if archived:

   Shell

   $ tar -C /opt/mongodb/backup/testbackup/20160809_1306 -xvf /opt/mongodb/backup/testbackup/20160809_1306/test1.tar test1/ test1/dump/ test1/dump/wikipedia/ test1/dump/wikipedia/pages.metadata.json.gz test1/dump/wikipedia/pages.bson.gz test1/dump/oplog.bson

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   $ tar -C /opt/mongodb/backup/testbackup/20160809_1306 -xvf /opt/mongodb/backup/testbackup/20160809_1306/test1.tar test1/ test1/dump/ test1/dump/wikipedia/ test1/dump/wikipedia/pages.metadata.json.gz test1/dump/wikipedia/pages.bson.gz test1/dump/oplog.bson

   This extracts to /opt/mongodb/backup/testbackup/…/dump

2. Verify you are restoring the correct backup to the correct host:

   • Check replica set naming in backup directories
   • Restore to PRIMARY in replica sets
   • Ensure majority availability for writes

3. Run mongorestore:

   Shell

   $ mongorestore --drop --host localhost --port 27017 --user secret --password secret --oplogReplay --gzip --dir /opt/mongodb/backup/testbackup/20160809_1306/test1/dump ... restoring wikipedia.pages ... replaying oplog done

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   $ mongorestore --drop --host localhost --port 27017 --user secret --password secret --oplogReplay --gzip --dir /opt/mongodb/backup/testbackup/20160809_1306/test1/dump ... restoring wikipedia.pages ... replaying oplog done

   • Use -vvv for verbose debugging if needed

4. Verify completion:

   • Look for replaying oplog
   • Look for done

Notes

For sharded environments:

• --oplog is not supported
• mongodump uses primaries (not ideal for production)
• Consider using mongodb_consistent_backup for safer backups

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