VM snapshots are a simple and effective way to roll a virtual machine back to a point in time. Mistakenly, some still view snapshots as a backup because they allow a VM to return to a previous state. Snapshots are not backups. It is dangerous to consider VM snapshots an actual backup copy of data. While many backup products use snapshots as part of a feature set, a snapshot alone is not a backup.
What are snapshots and when to use them
VM snapshots preserve the state and data of a virtual machine at a specific point in time so that if something goes wrong, you can go back to that point before it occurred.
The state of the machine includes the virtual machine’s power state of powered-on, powered-off or suspended. The virtual machine data consists of all files, memory, devices on the network, and virtual network interface cards.
Snapshots are generally used for development and testing purposes. VM snapshots can be used as a quick failsafe to be able to rollback before a patch, an upgrade, a test, or unsafe operations were performed on a VM.
Snapshots can be used in production environments but should be done with purpose. Snapshots should can be used if you are performing an update that could harm your system. But again, snapshots are not a full copy of a virtual hard disk. If the virtual disk is deleted or storage or infrastructure fails, snapshots cannot restore a VM.
Snapshots can also effect the performance of your VM if snapshots are kept running for a long period of time. VMware recommends only using 2 to 3 snapshots in a chain and never running a snapshot for more than 72 hours to keep performance high.
What makes backups different
Backups are standalone copies of your data that aren't connected to the VM and, therefore, offer a full VM copy so a single point of disk failure doesn't equal catastrophic data loss. Unlike snapshots, VM backups can be moved to the cloud, a separate location, or offsite for safe storage.
Beyond using backups as part of a sound business continuity plan, backups can provide granular features that snapshots cannot. Image-level backups offer a variety of recovery options including the ability to recover a entire VM or individual files or applications. Changed block tracking allows you to only back up data that has changed since the last backup so you can save storage space.
SEP Backup & Recovery Software offers users snapshots, image-level backups, single-file restore, encryption, deduplication, and a robust backup engine to support any recovery scenario. SEP supports VM snapshots for VMware, Hyper-V, Citrix XenServer, and Red Hat Virtualization, as well as storage snapshots. Snapshots should not be used for reliable data protection, however, they are a convenient feature to have at your disposal for testing and for a larger part of a backup operation.
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