This document compares the options available on Compute Engine for backing up and replicating your persistent disk data.
Options
| Feature | Summary | Use case | Optimized for |
|---|---|---|---|
| Snapshots | Captures the state of your disk at a particular point in time. Stored as differential copies for better performance and space efficiency. |
Long term data backup. | Long retention backup and geo-redundancy. |
| Machine images | Stores all the configuration, metadata, permissions, and data from one or more disks required to create a virtual machine (VM) instance. | Long term VM backup and restore. Instance cloning and replication. | VM consistency at the I/0 operation level or crash level. |
| Regional persistent disk | Replicates data synchronously across two zones in the same region. | High availability. Not designed for data backup. |
RTO: less than 1 minute RPO: 0 |
| Disk clones | Creates a live, attachable, fully provisioned disk with data from a source disk. | Quickly bringing up staging environments from production. Replication for backup verification or export offloading. Not designed for disaster recovery. |
Copy data management. |
| Images | Contains the set of programs and files required to boot an operating system on a VM instance. | VM import and fast disk creation. Quickly creating many VMs. |
Rapid disk creation. |
Best practices
Avoid temporary snapshots
To immediately create a copy of a disk in the same zone for verification or export, use disk clones instead of snapshots. Compared to disk clones, snapshots have longer copy times for upload and download.
Schedule hourly snapshots for backup and disaster recovery
Schedule hourly snapshots. If you require daily snapshots, consider scheduling snapshots every 6 hours.
Use images for fast and frequent disk creation across regions
To create many disks from a single data source, use images instead of snapshots. Because Compute Engine performs local caching in target zones, disk creation from images is faster than disk creation from snapshots.
To create backups of all disks attached to a VM instance, use machine images
Use machine images to create backups of all disks that are attached to a VM. A machine image can be used to backup multiple disks at a time to help ensure that the data captured in the machine image is consistent across all disks. A persistent disk snapshot can only back up a single disk at a time. For more information, see When to use machine images.