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- Backup a Small Sharded Cluster with
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Backup a Small Sharded Cluster with mongodump¶
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Overview¶
If your sharded cluster holds a small data set, you can
connect to a mongos using mongodump. You can
create backups of your MongoDB cluster, if your backup infrastructure
can capture the entire backup in a reasonable amount of time and if
you have a storage system that can hold the complete MongoDB data set.
See MongoDB Backup Methods and Backup and Restore Sharded Clusters for complete information on backups in MongoDB and backups of sharded clusters in particular.
Important
By default mongodump issue its queries to
the non-primary nodes.
Considerations¶
If you use mongodump without specifying a database
or collection, mongodump will capture collection data
and the cluster meta-data from the config servers.
You cannot use the --oplog option for
mongodump when capturing data from
mongos. As a result, if you need to capture a backup that
reflects a single moment in time, you must stop all writes to the
cluster for the duration of the backup operation.
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.
Changed in version 3.0.9: 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.
Procedure¶
Capture Data¶
You can perform a backup of a sharded cluster by connecting
mongodump to a mongos. Use the following
operation at your system’s prompt:
mongodump will write BSON files that hold a copy of
data stored in the sharded cluster accessible via the
mongos listening on port 27017 of the
mongos3.example.net host.
Restore Data¶
Backups created with mongodump do not reflect the chunks or
the distribution of data in the sharded collection or
collections. Like all mongodump output, these backups
contain separate directories for each database and BSON files
for each collection in that database.
You can restore mongodump output to any MongoDB instance,
including a standalone, a replica set, or a new
sharded cluster. When restoring data to sharded cluster, you
must deploy and configure sharding before restoring data from the
backup. See Deploy a Sharded Cluster for more information.