Snapshots and Backups: A Nearly Perfect Duo

Snapshots and backups are both crucial for data protection. However, to maximize their benefits, it’s essential to understand their capabilities.

As data volumes and value continue to grow, data has become an invaluable asset for businesses, governments, consumers, and cyber-criminals alike. Cyber-criminals will stop at nothing to steal information or block legitimate users from accessing it. Fortunately, organizations have various tools and methods to protect their data, including backups and snapshots. While these methods share some similarities, they are often mistakenly seen as interchangeable. This article will delve into the fundamental differences between backups and snapshots and how they can complement each other.

The Indispensability of Backups

Until recently, it was common to say that people were either backing up their data or were planning to do so. However, this saying is no longer accurate. It’s increasingly difficult to find individuals or businesses that don’t perform backups. Backups are typically created on a regular schedule (e.g., nightly or multiple times a day) and can include all files on a server, emails, or databases. By archiving data in backups, users are protected against accidental data loss caused by errors, accidental deletions, or other failures. This is why backups are often referred to as “security copies.”

There are several types of backups. The simplest is a full backup, which creates a complete copy of the data to a destination storage device. Other methods include differential and incremental backups. A differential backup only backs up data that has been added or changed since the last full backup. An incremental backup, on the other hand, uses the previous backup as a reference point rather than the initial full backup.

A full backup is a complete copy of the data. If each backup is 10TB, for example, it will consume an additional 10TB of storage. Creating a backup every hour would consume 100TB of storage in just 10 hours. For this reason, storing multiple versions of backups is not a common practice.

The Role of RPO

A challenge with backups is achieving a suitable Recovery Point Objective (RPO), which defines the maximum amount of data loss that can be tolerated and the maximum acceptable time between a failure and the restoration of a system to normal operation. Businesses have varying requirements—some may be satisfied with a 24-hour RPO, while others strive for an RPO as close to zero as possible. For example, losing even a small amount of data in manufacturing companies can lead to production line downtime, lost product batches, and significant financial losses.

Some businesses determine their RPO based on the cost of storage compared to the cost of data recovery. These calculations help determine the frequency of backups. Another approach is to assess risk levels. In this case, a company evaluates which data can be lost without significantly impacting the quality and continuity of its business.

Backups are not optimal for creating short recovery points. Snapshots are much better suited for this purpose, which is why the two technologies should be used together. Snapshots are the preferred solution when high RPO requirements must be met, such as in 24/7 environments like internet service providers.

Snapshots for Specialized Tasks

A snapshot is a point-in-time capture of stored data. Its main advantage is its creation time, which is typically measured in minutes or even seconds. Snapshots are usually created every 30 or 60 minutes and have minimal impact on production processes. They allow for quick recovery to previous file versions at multiple points in time. For example, if a system is infected with a virus, files, folders, or entire volumes can be restored to a state before the attack.

However, snapshots are often a feature of NAS or SAN storage and are stored on that storage. This means they occupy relatively expensive storage capacity, and if the storage fails, users lose access to recent snapshot copies. While individual snapshots do not consume much space, their combined size can increase, leading to additional processing costs during recovery. Therefore, it’s good practice to limit the number of stored copies. Experts recommend not storing snapshots for longer than the last full backup.

Furthermore, migrating a snapshot from one physical location to another does not allow for environment restoration, which is possible with backups. Since a snapshot is not a complete copy of the data, it should not be considered the sole backup and should be combined with backups. In summary, backups provide the ability to restore data over long RPOs, often quickly and in detail, down to the file level.

Types of Snapshots

While snapshot creation processes vary by vendor, there are several common techniques and integration methods.

• Copy-on-write: This method copies any blocks before they are overwritten with new information.
• Redirect-on-write: Similar to copy-on-write, but it eliminates the need for a double write operation.
• Continuous Data Protection (CDP): CDP snapshots are created in real-time, capturing every change.
• Clone/mirror: This is an identical copy of an entire volume.

Summary

Snapshots and backups have their strengths and weaknesses. Generally, backups are recommended for long-term protection, while snapshots are intended for short-term use and storage. Snapshots are typically useful for restoring the latest version of a server within the same infrastructure.

Both snapshots and file backups can be used together to achieve different levels of data protection, and this is actually the most recommended configuration for backup strategies.

Ready to strengthen your data protection? Explore the synergy between snapshots and backups with Storware Backup and Recovery. Contact us for a one-on-one demo.