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How does MongoDB complete the backup and restore of sharded cluster instances?

Created on 2025-06-18 15:27:10
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MongoDB provides several methods to back up and restore sharded cluster instances, ensuring data consistency and availability. Here’s how it works:

1. Backup Methods

a. Filesystem Snapshots (Recommended for Sharded Clusters)

  • How it works: Takes a snapshot of the data directories on each shard, config server, and mongos (if needed). Requires a filesystem that supports snapshots (e.g., LVM, EBS).
  • Steps:
    1. Stop balancer (sh.stopBalancer()).
    2. Lock each shard (optional, for consistency).
    3. Take filesystem snapshots.
    4. Unlock shards and resume balancer.
  • Example: On Tencent Cloud, you can use Cloud Block Storage (CBS) snapshots to capture the state of each shard’s data volume.

b. mongodump (For Smaller Clusters or Partial Backups)

  • How it works: Dumps data from each shard, config server, and mongos into BSON files. Less efficient for large clusters.
  • Steps:
    1. Run mongodump on each shard and config server.
    2. Use --oplog for point-in-time consistency.
  • Example: mongodump --host <shard-host> --out /backup/path --oplog

c. Cloud-Managed Backups (Tencent Cloud-specific)

  • How it works: Tencent Cloud’s TencentDB for MongoDB offers automated backups for sharded clusters, including full and incremental backups stored in COS (Cloud Object Storage).

2. Restore Methods

a. Restoring from Filesystem Snapshots

  • Steps:
    1. Stop the cluster.
    2. Restore snapshots to each shard and config server.
    3. Restart the cluster and rebalance data.

b. Restoring from mongodump

  • Steps:
    1. Use mongorestore to import data into each shard.
    2. Ensure the balancer is off during restoration.
  • Example: mongorestore --host <shard-host> --dir /backup/path --oplogReplay

c. Tencent Cloud’s Automated Restore

  • How it works: TencentDB for MongoDB allows restoring a sharded cluster from a backup point directly via the console, simplifying the process.

Best Practices

  • Consistency: Use --oplog with mongodump or stop the balancer for filesystem snapshots.
  • Testing: Verify backups by restoring to a staging environment.
  • Automation: Use Tencent Cloud’s scheduled backups for sharded clusters.

For Tencent Cloud users, TencentDB for MongoDB provides a managed solution with automated backups and one-click restore, reducing operational overhead.