When it comes to the world of backup, all that glitters is not… Truly backup.
To better protect your data, it’s essential to distinguish between approaches that could actually be considered backups and those that are better amalgamated under a heading that might be termed “backup.”
One procedure that is commonly confused with backup is replication. As the name suggests, replication involves making copies of data. Consider random array of independent disks (RAID) approaches, for example, particularly RAID 1 (disk mirroring).
If you’re reading this, then the expression “RAID is not backup” is probably not new to you (Learn more in our article on RAID). But equally, other forms of replication are not backups either, even though they are useful and important. Here’s why and what the differences are.
Difference
between backup and replication
What are the main differences between backup and replication? We would like to draw your attention to some distinctions. But first, let’s clarify the definitions:
What is replication?
As we mentioned, replication deals with making copies of data. Exactly what data is replicated will depend on what users want to protect.
Replication can cover: Copy,
- in real time
- Duplication of an entire
- Copy only aspects of the operating system, such as applications and settings
, files and folders from a computer
operating system at the operating system or disk level
Replication can be used to instantly and automatically reflect system resources to a secondary location, or in several of them.
For example:
- A replication program could instantly replicate changes to a critical database, such as a CRM MySQL table, to a second on-site copy for fast failover, and to an offsite copy for disaster recovery (DR) in the event that not all on-site resources are accessible
- Replication can be used to replicate all on-premises servers to cloud backup servers. Failover to cloud resources could happen automatically if on-site resources were unavailable, such as during a power outage (if the company had no backup power).
- Replicated copies are taken so that there is a secondary system that can mirror the primary system to ensure a smooth failover and minimize the Recovery Time Objective (RTO), that is, the maximum time it will take to restore operations.
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For replication systems, the RTO, for failover, would typically be measured in minutes. Unlike some backup use cases (e.g., hardware storage failures), these disruptions to routine operations are also expected to be temporary in nature and the company expects operations to be able to resume quickly on the primary system.
All of these data protection strategies are important to ensure business continuity by ensuring the provision of applications and systems in the event of a disaster and to making them available in real time. But, as we’ll soon explain, none of these approaches are considered endorsement.
What is backup?
The
backup creates a point-in-time copy of a file system or other digital asset (such as a database). Unlike snapshots, another “backup-like” technology, the backup contains the files themselves, rather than a note of changes since the last run.
A backup can be used for many disaster recovery (DR) use cases. Basically, if a change degrades stability or compromises data, restoring from a backup can return a system to its previous state. Some backup approaches (such as disk imaging) can even be used to back up a system to new hardware in the event of mechanical or physical destruction.
Finally, the backup can be used for compliance purposes and archived by companies that need to take an image of their system at any given time for regulatory reasons.
Further reading Backup FAQs: Everything You Need to Know
How They Work?
Backup
Backups typically involve making full copies of a source device to a destination media (full backups) or writing notes of additions, changes, and deletions (incremental or differential backups).
These approaches are used to ensure that a system can be restored to a specific point in time with one operation (restore from a full backup), or that the same can be accomplished by aggregating a series of files that notice changes in the file system.
Further reading Comparison of backup types
Replication
Here’s another difference between backup and replication: replication doesn’t involve taking historical copies, but simply replicates every change live, in real time. With replication, the moment the primary file system is changed, those changes are reflected on the target media.
The write process may occur instantaneously (synchronous replication) or may involve some latency (asynchronous or near-synchronous replication). The latter approach involves replicated storage that recognizes its write operations on primary storage and is popular on storage devices such as network-attached storage (NAS) devices.
Use
cases
Backups are used to ensure that there is a backup point for everything from user endpoints, such as desktops, to servers. If there is a machine that businesses need to make sure can be restored in case of downgrade, accidental deletion or other error, then backups are the tool of choice.
Further
reading Desktop
Backup with MSP360
Further Read Server Backup with MSP360
Replication
Replication is used to protect mission-critical applications such as CRM servers, payment processing machines, and anything else the business needs to have operational all the time. If even five minutes of downtime is too much, a replica will be provisioned for failover.
Which one costs more?
Backup
Backup is usually the cheaper of the two approaches. This is because, to perform a backup, users usually only need to provision some storage and a backup program to run operations.
Further reading Benefits of
Cloud Storage Replication Explained To set up a replication system, on the other hand, users
would need to provision parallel resources
.
To provide replication for a storage center, for example, users would have to configure the computer’s storage with the same capacity as the primary storage system at a remote site. This could involve substantial hardware costs.
Which one needs more resources?
As a general principle, replication approaches also need more resources.
While a backup manager,
software, and some storage media may be sufficient to ensure a backup strategy within a small business, to set up proper replication of a mission-critical system, companies may need to allocate significant resources to the deployment. They may also need to implement new business processes, teach staff how to manage failover, and invest in new infrastructure to support the ongoing operation of replication systems.
Benefits Head to Head
Backup approaches
:
- Easy to implement: Users simply need to determine which backup approach is appropriate to support their RTO and recovery point (RPO) objective
- Provide high isolation—Many backup systems, such as tape libraries, are stored cold. In addition, they are usually not connected live to the primary systems. Therefore, if the primary system is attacked by a virus or ransomware, the backup will remain clean.
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Further reading Backup best practices in ransomware protection strategy
- are inexpensive: comparatively speaking, backup approaches don’t cost much to set up and maintain
.
Replication
approaches:
- Focus on disaster recovery: If what is required is a fast RTO, replication approaches have the advantage over backups
- Provide high availability: Similarly, for resources that need to be highly available, such as components of a cloud, ensuring replication makes more sense than backup. Of course, in many cases both must be used!
- fast RTOs: RTOs for backup are typically longer than for replication systems.
.
Provide
Each
approach also has its disadvantages
.
Backup
For backup approaches, there can be a relatively long time between backup snapshots. The period of time between two backups is called the recovery point objective (RPO). The longer the RPO, the more data a company will lose should recovery from that backup be required.
In addition, the RTO is usually longer. This is because an entire operating system, potentially across an entire network of servers, needs to be written. The RTO for replication is often almost non-existent, as these are typically parallel systems that run and update continuously.
The main disadvantage of replication is that it is more expensive to maintain than backups. Backups can use highly cost-effective LTO storage by storing petabytes of data at low cost. For replication, because systems are expected to be ready for near-instantaneous failover, this kind of storage is sometimes not viable.
However, there is a key disadvantage to backups: they cannot be used to restore historical system states. If a primary device suffers a ransomware attack, for example, then ransomware will quickly spread on the replicated device. If the primary system needed to be restored to a point in time before it became infected, then a backup, rather than a replica, would be required. For system administrators performing backups, systems could simply revert to a restore point before they are compromised.
Which one do you need?
Companies can commonly be found operating both backup and replication systems. A CRM server, for example, could be backed up regularly to ensure restorability in the event of hardware failure. Meanwhile, the business could provision a parallel replication server that could be used for high availability failover in the event that the primary system was unavailable due to a temporary outage in service.
In
today’s business environment, data protection often requires a multifaceted approach. However, to use these approaches efficiently, you need to see the difference between backup and replication, and understand when each method is most appropriate.
Any system with a high availability requirement, requiring near-zero downtime, should be replicated to a parallel resource.
In the meantime, backups remain essential. They can be used to roll back changes that degrade system performance (a use case for which replicating copies would be useless). In addition, for cybersecurity, administrators must retain the ability to restore a system to a point in time before it became infected.
