Snapshots and Backups Are Better Together

Snapshots and backups. You hear these terms thrown around a lot, and sometimes interchangeably. But while they may sound similar, there are some important differences. Both can provide a way to recover systems and data to their original state at a point in time, but they go about it in different ways.

What Is a Backup?

If you’re reading this blog, it’s safe to assume you know what backup means.

As a noun, essentially, it’s a copy of your data and files. Traditionally, that copy is placed in a different location than the original content–making it ideal for disaster recovery, to restore servers after a server failure, or, more commonly, to restore data accidentally deleted by users or in some cases maliciously corrupted by ransomware.

As a verb, backup is the process of creating and maintaining multiple backup copies of your data. Depending on the type and amount of data, backups can take minutes, hours or even days to complete, meaning there may end up being significant differences between your last complete backup, based on when the backup started and your live production data.

For this reason, continuous replication of data is often desirable to reduce data loss in the event of a disaster to meet corporate recovery point objectives measured in minutes versus more typical once-a-night backup schedules. Often, backups are stored for long periods of time and may serve the function of an archive for various purposes, such as legal discovery and compliance. In many cases, cloud-based storage can be a cost-effective approach for long-term backup data retention. However, it is important to consider the time that would be required to access large amounts of cloud-based data for recovery. Cloud is generally not suitable for recent backup copies that are most likely to be needed to recover systems and data quickly to meet corporate recovery time objectives (RTO).

What Is a Snapshot?

As the name implies, snapshots provide a quick “picture” of a server (including its files, software and settings) at a particular point in time. Generally, snapshots are instant, and preserve a point-in-time state without having to move or copy existing data at all. For this reason, most modern backup approaches actually rely on snapshot technology to provide a stable, unchanging point-in-time image to do a backup of, versus doing backup of the live system and data and having to contend with open files and active applications changing data during the backup. In systems such as HC3, snapshots can also be replicated to a secondary system located in another location or even a cloud-based service (DRaaS).

When using a snapshot to restore a server, that server will revert back to the exact state it was in when the snapshot was taken. For that reason, snapshots are a quick and effective way to “roll back” to that point in time.

Snapshots don’t make a full copy of all data, so they can be very space-efficient. And, in the case of HC3, a snapshot actually consumes nearly zero additional storage at the time it is taken.

However, as data blocks in the live system change through normal production use, the snapshot needs to preserve the original snapshot content, as well; this means that the storage space attributed to a snapshot will grow over time as the snapshot data diverges from the live system. Therefore, snapshots are generally best for shorter-term storage retention.

Snapshots at the VM level allow for easy, instant, point-in-time recovery, providing protection against ransomware, malware and accidental file deletion. Snapshots can be used to recover entire VMs or individual files. Support for hundreds of snapshots per VM plus flexible scheduling and retention options enable multiple levels of protection for VMs, based on the need for each individual VM.

The Differences Between Snapshots and Backups

So, to be clear, snapshots alone are not true, independent backup copies. However, they are very useful for certain purposes, like development and testing. For instance, a snapshot can be used as a quick failsafe in case you need to