Home VM Tips VM Snapshot vs. Backup

VM Snapshot vs. Backup

2022-06-15 | Iris Lee

Table of contents
  • What is a snapshot?
  • What are the pros & cons of a snapshot and when to use it?
  • What is a backup?
  • What are the differences between a snapshot and a backup?

f03cddd9b2ef4501bf490bb78b50088.png

For enterprise production, the most important thing is data. It is the lifeline of business survival, whose damage or loss can lead to serious economic consequences, so the protection of data is crucial.

Data protection solutions can be divided into snapshots and backups, so what are the differences between these two, and what scenarios are they applicable to? First, we have to make clear that snapshots do not equate to backups. When data is in danger, snapshots and backups have different jobs, and the two different mechanisms are used to respond to different needs.

What is a snapshot?

According to SNIA (Storage Networking Industry Association), a VM snapshot is a point-in-time copy of a defined collection of data, or any type of container supported by the system, which could be of files, LUNs, or file systems. It is a protection of the state of data at a specific point in time, saving only those data that have changed beyond the full copy. In other words, if the data has not changed, the snapshot will not save additional data, and the snapshot can be seen as a freeze of the data at a specific point in time.

What are the pros & cons of a snapshot and when to use it?

Snapshot can be applied to both backup and recovery scenarios. Being smaller has little effect on the server, it enables data integrity, app availability, and quick recovery by reverting to the state. Nevertheless, snapshots are vulnerable to a production sever disruptions and consume a significant portion of the primary storage capacity over time if they are used to back up. So, they are commonly used for development and testing purposes instead of prolonged data protection. Another fly in the ointment is the lack of granularity, though snapshots can be used as a quick failsafe that rolls back to a certain period, they fail to perform advanced recovery features like granular restore.

What is a backup?

SNIA defines a backup as a collection of data stored on (usually removable) non-volatile storage media for purposes of recovery in case the original copy of data is lost or becomes inaccessible. Basically, backup is the standalone full copy of data that makes recovery possible in cases of disasters or human errors. Unlike snapshots, backups, independent of raw volumes, are allowed to be exported and stored elsewhere. Generally, backups are divided into three categories, full backup, incremental backup, and differential backup.

Types:

Full backup: The process of producing at least one additional copy of all data files that an organization desires to secure in a single backup procedure. A full backup has the most complete backup data and therefore the greatest data protection; on the other hand, the huge amount of data backup at one shot takes up more room than other methods. Nonetheless, it is inevitable to initiate a full backup for comprehensive data protection since it’s the foundation of all the other backup methods and recovery resources.

Incremental backup: An incremental backup is one in which each subsequent copies of the data only contain the portion that has changed since the last backup copy was generated. When one conducts the incremental backup, the first will necessarily be a full backup and all ensuing backups will be changed data blocks since the last backup, so the backup time can be shorter than doing only full backups.

Differential backup: A backup strategy that also starts with an initial full backup, and later saves all changed data since the last full backup. The amount of time required to complete a differential backup is generally between an incremental backup and a full backup, and so is the data size of it.

What are the differences between a snapshot and a backup?

A snapshot is an immediate “photo” that records the status of the stored data at exact time points. Whereas backup is a duplicate of current data stored in the devices. Backup copies of chosen files once launched and keep them in a separate location.

Storage locations: Backups could be stored in the same server, same drive, cloud, or another location, which means backups are portable and movable; While snapshots can only be stored in the same location where the original system data is located.

Status: Backups may have differences according to the start and end time; snapshots is just a photo of the server at a given time.

Scenarios: Snapshots are useful for development and testing; backups protect digital assets for long periods of time.

Function: Snapshots copy the object metadata at certain points in time; backups copy the complete database, applications, VMs, and more.

Duration: Creating and copying backups can be a long process, which is unavoidable; and snapshots are instantaneous that take less time.

Aims: Backups are easily restored and generally verifiable, which are designed for long-term data protection. Snapshots do not equal backups, yet they can be a part of the backup process and often are deleted after the process. They are made for short-term solutions.

By comparison, we know that a snapshot is a technology that captures the status at some point and backup is more of a process of copying data for longer-term protection. Despite their differences, snapshots keep the backup window shorter and help ensure data consistency. So, data solution vendors often integrate these two to boost efficiency.

Vinchin Backup & Recovery delivers efficacious data solution features covering image-level backup, backup copies, snapshot-based CBT /SpeedKit  (both are technologies for accelerating incremental backup process), and specialized transmission modes for the backup of 11 main virtualizations such as VMware, XenServer, oVirt and etc.

For more advanced backup and recovery functions such as instant recovery and granular restore, download the 60 days free trial of Vinchin Backup & Recovery.

Share on:

Categories: VM Tips