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Back Up and Restore with MongoDB Tools¶
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This tutorial describes the process for creating backups and restoring data using the utilities provided with MongoDB. The mongodump and mongorestore utilities work with BSON data dumps, and are useful for creating backups of small deployments. For resilient and non-disruptive backups, use a file system or block-level disk snapshot function, such as the methods described in the MongoDB备份方案 document.
Because mongodump and mongorestore operate by interacting with a running mongod instance, they can impact the performance of your running database. Not only do the tools create traffic for a running database instance, they also force the database to read all data through memory. When MongoDB reads infrequently used data, it can evict more frequently accessed data, causing a deterioration in performance for the database’s regular workload.
When backing up your data with MongoDB’s tools, consider the following guidelines:
- Label files so that you can identify the contents of the backup as well as the point in time that the backup reflects.
- Use an alternative backup strategy such as Filesystem Snapshots or MongoDB Cloud Manager if the performance impact of mongodump and mongorestore is unacceptable for your use case.
- Use --oplog to capture incoming write operations during the mongodump operation to ensure that the backups reflect a consistent data state.
- Ensure that your backups are usable by restoring them to a test MongoDB deployment.
参见
MongoDB备份方案 and MongoDB Cloud Manager Backup documentation for more information on backing up MongoDB instances. Additionally, consider the following reference documentation for the MongoDB import/export tools:
Binary BSON Dumps¶
The mongorestore and mongodump utilities work with BSON data dumps, and are useful for creating backups of small deployments. For resilient and non-disruptive backups, use a file system or block-level disk snapshot function, such as the methods described in the MongoDB备份方案 document.
Use these tools for backups if other backup methods, such as MongoDB Cloud Manager or file system snapshots are unavailable.
Procedures¶
Back Up a Database with mongodump¶
Required Access¶
To run mongodump against a MongoDB deployment that has access control enabled, you must have privileges that grant find action for each database to back up. The built-in backup role provides the required privileges to perform backup of any and all databases.
在 3.2.1 版更改: The backup role provides additional privileges to back up the system.profile collections that exist when running with database profiling. Previously, users required an additional read access on this collection.
Basic mongodump Operations¶
The mongodump utility backs up data by connecting to a running mongod or mongos instance.
The utility can create a backup for an entire server, database or collection, or can use a query to backup just part of a collection.
When you run mongodump without any arguments, the command connects to the MongoDB instance on the local system (e.g. 127.0.0.1 or localhost) on port 27017 and creates a database backup named dump/ in the current directory.
To backup data from a mongod or mongos instance running on the same machine and on the default port of 27017, use the following command:
mongodump
The data format used by mongodump from version 2.2 or later is incompatible with earlier versions of mongod. Do not use recent versions of mongodump to back up older data stores.
You can also specify the --host and --port of the MongoDB instance that the mongodump should connect to. For example:
mongodump --host mongodb.example.net --port 27017
mongodump will write BSON files that hold a copy of data accessible via the mongod listening on port 27017 of the mongodb.example.net host. See Create Backups from Non-Local mongod Instances for more information.
To specify a different output directory, you can use the --out or -o option:
mongodump --out /data/backup/
To limit the amount of data included in the database dump, you can specify --db and --collection as options to mongodump. For example:
mongodump --collection myCollection --db test
This operation creates a dump of the collection named myCollection from the database test in a dump/ subdirectory of the current working directory.
mongodump overwrites output files if they exist in the backup data folder. Before running the mongodump command multiple times, either ensure that you no longer need the files in the output folder (the default is the dump/ folder) or rename the folders or files.
Point in Time Operation Using Oplogs¶
Use the --oplog option with mongodump to collect the oplog entries to build a point-in-time snapshot of a database within a replica set. With --oplog, mongodump copies all the data from the source database as well as all of the oplog entries from the beginning to the end of the backup procedure. This operation, in conjunction with mongorestore --oplogReplay, allows you to restore a backup that reflects the specific moment in time that corresponds to when mongodump completed creating the dump file.
Create Backups from Non-Local mongod Instances¶
The --host and --port options for mongodump allow you to connect to and backup from a remote host. Consider the following example:
mongodump --host mongodb1.example.net --port 3017 --username user --password pass --out /opt/backup/mongodump-2013-10-24
On any mongodump command you may, as above, specify username and password credentials to specify database authentication.
Restore a Database with mongorestore¶
Access Control¶
To restore data to a MongoDB deployment that has access control enabled, the restore role provides access to restore any database if the backup data does not include system.profile collection data.
If the backup data includes system.profile collection data and the target database does not contain the system.profile collection, mongorestore attempts to create the collection even though the program does not actually restore system.profile documents. As such, the user requires additional privileges to perform createCollection and convertToCapped actions on the system.profile collection for a database.
If running mongorestore with --oplogReplay, the restore role is insufficient to replay the oplog. To replay the oplog, create a user-defined role that has anyAction on anyResource and grant only to users who must run mongorestore with --oplogReplay.
Basic mongorestore Operations¶
The mongorestore utility restores a binary backup created by mongodump. By default, mongorestore looks for a database backup in the dump/ directory.
The mongorestore utility restores data by connecting to a running mongod or mongos directly.
mongorestore can restore either an entire database backup or a subset of the backup.
To use mongorestore to connect to an active mongod or mongos, use a command with the following prototype form:
mongorestore --port <port number> <path to the backup>
Consider the following example:
mongorestore dump-2013-10-25/
Here, mongorestore imports the database backup in the dump-2013-10-25 directory to the mongod instance running on the localhost interface on the default port 27017.
Restore Point in Time Oplog Backup¶
If you created your database dump using the --oplog option to ensure a point-in-time snapshot, call mongorestore with the --oplogReplay option, as in the following example:
mongorestore --oplogReplay
You may also consider using the mongorestore --objcheck option to check the integrity of objects while inserting them into the database, or you may consider the mongorestore --drop option to drop each collection from the database before restoring from backups.
Restore Backups to Non-Local mongod Instances¶
By default, mongorestore connects to a MongoDB instance running on the localhost interface (e.g. 127.0.0.1) and on the default port (27017). If you want to restore to a different host or port, use the --host and --port options.
Consider the following example:
mongorestore --host mongodb1.example.net --port 3017 --username user --password pass /opt/backup/mongodump-2013-10-24
As above, you may specify username and password connections if your mongod requires authentication.