Problem Statement
What are the different backup and recovery strategies for MongoDB? Compare their advantages and disadvantages.
Explanation
MongoDB offers several backup and recovery strategies, each with different trade-offs between consistency, performance impact, and ease of use. Choosing the right strategy depends on your recovery time objectives, data size, and operational requirements.
First, mongodump and mongorestore are utility tools that create logical backups by reading documents and writing them to BSON files. Advantages include simplicity, platform independence, and ability to backup specific databases or collections. Disadvantages are that they are slow for large datasets, do not capture a point-in-time snapshot by default, and require significant I/O resources.
Second, file system snapshots create binary copies of data files at the storage layer. Cloud providers and storage systems offer snapshot features that create consistent copies almost instantly. Advantages include speed, minimal performance impact, and point-in-time consistency. Disadvantages are dependency on specific storage systems and typically requiring the entire data directory.
Third, MongoDB Cloud Manager and Ops Manager provide continuous backup with point-in-time recovery. They take periodic snapshots and capture oplog entries between snapshots, allowing you to restore to any point in time. Advantages include automated scheduling, point-in-time recovery, and minimal manual intervention. Disadvantages are cost for cloud services and complexity for on-premises Ops Manager.
Fourth, delayed replica set members can serve as a live backup. Configure a secondary with a replication delay of several hours. If data corruption or accidental deletion occurs, you can recover from the delayed member before it replicates the problem. Advantages include continuous availability and simple recovery. Disadvantages are resource overhead and limited recovery window.
Best practices include testing your backup and recovery procedures regularly, storing backups in a different location or region, encrypting sensitive backups, and documenting recovery procedures. Combine multiple strategies for defense in depth.