Data Domain: DD BoostFS Plug-In Application Validation and Best Practices for MongoDB: Mongodump

MongoDB provides the mongodump utility to dump the whole database to a wanted location.
Dump the database to a BoostFS file system mounted on the server where the MongoDB mongod database process runs.
mongodump backs up the database, which can consist of several collections.

Set up BoostFS

Install BoostFS on the MongoDB server to be backed up.

To perform backups:

# mongodump --db testdb --numParallelCollections 5 --out /backup/

# mongodump --db <database_name> --numParallelCollections <no_parallel_collection_to_export> --out <path_to_boostfs_drive> --host <mongo_instance_hostname>

The use of the numParallelCollections option in mongodump enables parallel n collections backups. If there are more than n collections in the mongodb database, they are backed up n collections at a time.

This creates the testdb directory under /backup and stores all the collections.

The numParallelCollections enables the use of multiple write streams (one per collection) to the Data Domain system.

Improving performance depends on this option and also if it can be used, depending on the collection data base.

If this option is used, but performance remains poor, then it is because of the data base collection.

Example: If there is a collection that is of a larger size, mongodump runs a single backup job for this collection, and only one connection is made.
 

How to perform a restore: Use mongorestore to restore the database dump to a running mongod instance.

To restore the database data backed up to the boostfs mount point /mnt/mongo-bkp using mongodump, use the mongorestore command as shown below. This restores the files to the demo-restore database. 

# mongorestore --db demo-restore /mnt/mongo-bkp/data/
2016-08-24T12:58:08.675-0400 building a list of collections to restore from /mnt/mongo-bkp/datadir
2016-08-24T12:58:08.680-0400 reading metadata for demo-restore.cc from /mnt/mongo-bkp/data/cc.metadata.json
2016-08-24T12:58:08.757-0400 restoring demo-restore.cc from /mnt/mongo-bkp/data/cc.bson
2016-08-24T12:58:11.397-0400 restoring indexes for collection demo-restore.cc from metadata
2016-08-24T12:58:11.397-0400 finished restoring demo-restore.cc (75000 documents)
2016-08-24T12:58:11.398-0400 done

Restores can also be done in parallel using multiple streams. mongorestore first opens the metadata file, keeps it open, begins reading the datafile, and closes both files, for each collection.

Performance: The following chart shows the write and read performance for this application with BoostFS compared to the same workload over NFS.
The percentages represent the amount of incremental performance measured in the labs for this use case. The write figures are based on multiple databased backups (0-3) with a change rate of 10%.

For recovery, testing has shown the restore performance of BoostFS to be about the same as NFS.

Best practices - Mongodump

1. Mongodump writes the backup files to the Data Domain systems in an uncompressed format, with using either the Wired Tiger or MMAPV1 storage engine.
2. MongoDB backups using Mongodump always dump whole databases, which are full backups.
3. One Mongodump stream per MongoDB server
4. Up to 63 streams per BoostFS plug-in

More command options for boostfs mount from the Configuring and using BoostFS for both Windows and Linux Guides: