Help Center/ GaussDB(DWS)/ User Guide/ GaussDB(DWS) Cluster O&M/ Backing Up and Restoring a GaussDB(DWS) Cluster/ Overview
Updated on 2024-10-21 GMT+08:00
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Overview

A snapshot is a full or incremental backup of a GaussDB(DWS) cluster at a specific point in time. It records the current database data and cluster information, including the number of nodes, node specifications, and database administrator name. Snapshots can be created manually or automatically. For details, see Manual Snapshots and Automated Snapshots.

If you restore a snapshot to a new cluster, GaussDB(DWS) creates a new cluster based on the cluster information recorded in the snapshot, and then restores data from the snapshot. For more information, see Restoring a Snapshot to a New Cluster.

If you restore a snapshot to the original cluster, GaussDB(DWS) clears the existing data in the cluster, and then restores the database information from the snapshot to the cluster. For more information, see Restoring a Snapshot to the Original Cluster.

The snapshot backup and restoration rates are listed below. (The rates are obtained from the test environment with local SSDs as the backup media. The rates are for reference only.) The actual rate depends on your disk, network, and bandwidth resources.)

  • Backup rate: 200 MB/s/DN
  • Restoration rate: 125 MB/s/DN
  • Backing up the cluster is essential for maintaining data reliability, especially when the service provider cannot restore data through upstream re-import. This helps prevent data loss caused by human or other factors.
  • OBS snapshot storage space and billing description
    • The cluster storage is provided by GaussDB(DWS) free of charge. Cluster storage = Storage space per node x Number of nodes
    • GaussDB(DWS) provides some free-of-charge storage space for you to store snapshot data generated in cluster backup. However, if you use more space than the free-of-charge storage space, the exceeded part is charged as per OBS billing rules. For details, see the OBS pricing details.
  • The dependency of the snapshot service is as follows:
    • The snapshot management function depends on OBS or NFS.
    • The backup device employs disk mounting mode for NFS backup media, reliant on the cloud-based SFS-Tubor service. For details, see 11.1.3.2 Automatic Snapshot Policy.
    • Only the snapshots stored in OBS can be used to restore data to a new cluster.
  • The new GaussDB(DWS) cluster created based on the snapshot must have the same configurations as the original cluster. That is, the number and specifications of nodes, memory, and disks in the new cluster must be the same as those in the original cluster.
  • If you create a new cluster based on a snapshot without modifying parameters, the parameters of the new cluster will be the same as those of the snapshot.
  • The hybrid data warehouse (standalone) does not support snapshots.
  • Only DWS 3.0 clusters of 9.0.2 and later versions support the snapshot function.
  • To perform snapshot restoration of a GaussDB(DWS) cluster billed in hybrid mode, you can choose either yearly/monthly or pay-per-use billing. For example, if the cluster has three nodes of each billing type, restoring the cluster will change the billing mode of all six nodes to either pay-per-use or yearly/monthly.
  • During snapshot creation, do not perform the VACUUM FULL operation, or the cluster may become read-only.
  • Snapshot creation affects disk I/O performance. You are advised to create snapshots during off-peak hours.
  • During the snapshot creation, some intermediate files are retained, which occupy extra disk space. Therefore, create snapshots in off-peak hours and ensure that the disk capacity usage is less than 70%.