What is a Snapshot Backup?

You have a lot of options when it comes to protecting your business data. “Snapshots” are common today, but it’s a term often confused with traditional backup. While snapshots and backups refer to copying your data, they aren’t exactly the same.

What is a Snapshot Backup?

It is important to understand that snapshots and backups are two distinct methods of making a copy of your data.

A snapshot is not the same as a traditional backup copy. A snapshot is a point-in-time copy of data taken from an operating system, software application, or disk. It captures the exact state of the data at a specific moment with all its settings, preserving it as a record to be used as an integral part of the backup and recovery process.

As a comparison, it’s similar to taking a photo of what’s stored on a device or virtual machine (VM) at any particular moment. Organizations with robust backup and recovery strategies often take advantage of snapshots as an important component of their short-term data retention practices to mitigate natural, human error, or cyber risk.

How do snapshots work?

A snapshot creates files with extensions. These files are placed on the same storage infrastructure as the host system. For example:

• .vmdk file: A virtual disk file that contains the raw data in the base disk.
• delta.vmdk file: An incremental disk, represented in the format of a .00000x.vmdk file, that captures all changes between the current state of the virtual disk and the last snapshot taken.
• vmsd file: A centralized file containing snapshot information and metadata. Snapshot managers regard this file as their primary source of information.
• .vmsn file: The snapshot state file that stores the current configuration and optionally the running state of a virtual machine (VM). It allows you to revert to a running state of the VM.

Pros of Snapshot Backup

• Compared to backups, faster rollback to an earlier point in time
• Rapidly and easily created without affecting the production server
• Reduces the total cost of ownership by removing the requirement for Windows native backup solutions (TCO)

Cons of Snapshots

• Being open to problems that affect the production server
• Utilizes a sizable portion of the primary storage capacity
• Lacks selectivity; you must retrieve files in their completeness because you cannot restore individual files from snapshots.

Types of Snapshot Backup

There are many widely used methods for creating and integrating snapshots, even though how they are executed varies from vendor to vendor.

Copy-on-write
When an I/O request tries to modify a storage block under copy-on-write, the block is copied first and kept by the snapshot to which it relates. This maintains consistency for that storage snapshot, which includes pointers to blocks that have not changed and duplicates of those that have.

Redirect-on-write
When new blocks are generated with redirect-on-write, only one write is necessary for the snapshot backup. The original and the snapshot are referred to whenever the present state of the data is mentioned. Those differences must be reconciled back to the parent when snapshots are deleted.

Continuous data protection (CDP)
Since CDP snapshots are taken in real-time, they are updated each time an alteration is made to the original copy. In addition to automatically preserving every version of the user’s information locally or at the target repository, it provides continuous data modification tracking and recording. However, frequent snapshot updates and creation degrade network speed and bandwidth.

Clone/mirroring
The multiple types of cloning are related to snapshots but have entirely distinct mechanisms. A clone is an exact duplicate of a storage unit at its most basic level. Not just original and updated area photos but the entire thing.

Snapshot vs Backup

Snapshot backups are primarily used to restore systems, virtual machines, and disks or drives to a running state and serve as a recovery point for the system when a snapshot is taken. It is not equivalent to a backup copy, it does not store data itself but only defines where and how data is stored and organized.

Typically, snapshots are created using disk/system images or system restore and recovery software. However, most backup software can also take snapshot backups and restore the system using snapshots.

Conclusion

Many people have discovered that using snapshots to recover lost data or virtual infrastructure is unreliable. Organizations should always have backups in place to have an independent method for business continuity, even though they have exceptional use cases and can be employed safely within the limits of their designed meaning and purpose.