Key concepts and best practices for snapshot backup

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.

What is a snapshot used for?

A snapshot is typically used to rapidly restore an operating system, a server, or a virtual machine (VM) and disk—to a granular level.

An organization will need a comprehensive backup process and strategy that includes a combination of snapshot copies and long-term backup solutions to meet both immediate and extended data storage requirements.

Snapshot copies are most efficient for short-term recovery scenarios and are often used as an immediate recovery option in case of data loss, corruption, or system failures, and represent a frozen image of all the data at the time of the backup, allowing for fast, and granular recovery to a specific known good state. They can be stored in the same location as the original system offering quick access to the backups, with some limits to its usefulness in certain disaster recovery scenarios. They can be stored off-site in a secondary location, such as a secondary data center or cloud. A secondary location will offer a layer of data protection that safeguards against localized incidents like natural disasters, cyberattacks, or site-level failures.

Snapshots are typically used for:

• Point-in-time recovery: Environments that require regular, fast backups, like databases or applications, that have very high transaction volumes.
• Rapid recovery: Organizations can recover data to specific point-in-time. For example, VM environments use snapshots for rapid data recovery and for replication purposes.
• Space efficiency: Snapshots copies can optimize storage usage. Modern snapshots technologies such as dedupe and incremental snapshots can minimize the storage space required.
• Testing and development: Snapshots provide a reliable and consistent dataset for Test/dev purposes. They can provide unlimited clones of data that enable development to proceed without disrupting daily workflows.
• Backup and recovery: A data center can use snapshot copies for data protection and disaster recovery, allowing data to be restored quickly to a known good state.

How do snapshots work?

Imagine collaborating online on a lengthy report with different teams or individuals who update it throughout the day. A snapshot would be like making a copy of the report as it stands at any moment, creating a point-in-time copy. Most likely, someone will make changes to the original document and save them periodically. They then would create a snapshot at regular intervals, but each snapshot would only copy data that had changed since the last snapshot.

Suppose someone accidentally deleted a section, or even if a technical glitch lost the entire report. With snapshots, it wouldn’t be necessary to start from zero. The user could simply restore the most recent copy or the last known good copy. Lost work would be limited to only the time since the last copy was made.

What are the benefits and disadvantages of a snapshot?

The main benefit of a snapshot is that it can be created very rapidly—and frequently—allowing for a quick and straightforward way to recover files or data if something goes wrong. Data can be restored to a specific point in time when it was in a good state. This allows organizations to back up large volumes of data regularly, minimizing the risk of losing important data in cases of disasters, whether technical, natural, or human-made.

Other benefits:

• Snapshots are quick to create and they are relatively small. Creating them saves time and allows you to create backups without interrupting production servers.
• Snapshots improve the availability of apps, allowing organizations to quickly recover from system outages, simplify the backup of large volumes of data, and minimize exposure to data loss.
• Snapshots can be scheduled to reduce the necessity of backup windows and thus lower the total cost of ownership (TCO).
• Snapshots ensure data is captured in a consistent manner, such as when files and related information are saved together at the same point in time. It will prevent any inconsistencies or incomplete data from being backed up.
• A server restore can be started instantly from a snapshot, minimizing downtime and further business interruption.

However, snapshots have some disadvantages, too:

• Because a snapshot is normally stored on the same storage device network as the original, if something goes wrong with either, the organization risks losing snapshots and the source systems and data.
• If a server has too many snapshots, the system will slow down.

What is the difference between a snapshot vs backup?

The term snapshot is often used interchangeably with the term backup, but they are not the same function. Yes, they both make copies of systems and data, but they do so in different ways.

• Backup files only include the file system. Snapshots can be made of different types of systems. These include files, apps, settings, and more.
• A backup is typically stored in a different location (or in multiple locations) than the original data to keep it safe in case of a disaster. A snapshot is stored in the same place as the original.
• A backup is meant for long-term storage, whereas snapshots are generally useful if individuals or teams need to revert to a very recent version of the server on the same network.
• Backups can have differences between when the backup began and ended. Snapshots are like still photos of the system that capture it precisely as it was at a particular time.
  The process of creating backups can be long and tedious. Snapshots are instantaneous and take a lot less time to complete.
• Backup restore time varies depending on the volume of data backed up. Snapshots can be used to restore servers quickly by rapidly reverting them to the state they were in when the snapshot was taken.

Snapshots and data backups are frequently used together to provide holistic protection of data. Indeed, this kind of hybrid strategy of using a combination of data snapshot and backup techniques is widely considered a best practice in data protection and cyber resilience.

Cohesity and snapshot copies

Business today operates 24/7/365. Organizations can’t afford to lose access to their data for even a very small fraction of that time. This means absolutely minimizing recovery time objectives (RTO) and recovery point objectives (RPO).

The Cohesity data security and management platform was designed with the patented Cohesity snapshot technology called SnapTree™ at its foundation to deliver robust continuous data protection that:

• Provides insurance against data loss due to accidentally deleted files, application crashes, or data corruption.
• Retains data for long periods of time to satisfy compliance and regulatory requirements.
• Minimizes RPO and RTO with a distributed, web-scale platform.

Because Cohesity has innovated snapshot technology, it is considerably different from traditional snapshot offerings. For starters, legacy storage solutions use copy-on-write/redirect-on-write snapshot technology to create copies of data. These snapshots of a file system form a chain that tracks the changes made to a set of data. This is the foundation for storing copies of data in a snapshot.

With this methodology, every time a change is captured, a new link is added to the chain. These chains grow with each successive snapshot. This means that the time it takes to retrieve data on a given request also grows because the system must re-link the chain to access that data every time. This is a highly inefficient process that is unable to handle the shorter RPO and RTO metrics required by today’s digital businesses.

In contrast, SnapTree technology from Cohesity uses a distributed-redirect-on-write (DROW) snapshot mechanism that is both faster and more scalable than read-on-write snapshots. The design is optimized for write performance, so any changes are redirected to new blocks. Additionally, all nodes participate in this process, thereby leveraging the scalability elements of the Cohesity cluster.

SnapTree, available as part of the Cohesity Data Cloud platform, delivers the following benefits, helping organizations to:

• Achieve faster backup and restores with a reduction in RTO and RPO windows by over 90%.
• Obtain pay-as-you-grow scaling that ensures maximum data reduction while backups are readily available for instant recovery and cloning.
• Reduce TCO by limiting storage growth from multiple data copies.