Backup and Replication Explained: What’s the Difference?
2022-06-02 | Charley
Some when establishing their own proper data protection plan for the first time might get confused by the two seemingly identical strategies: backup and replication. It seems like they both point to the method of saving another data copy to protect initial data from loss—you can say it’s partly right, but not all. Let’s dig deep into the essence of these two concepts, and figure out what role of each is in the field of disaster recovery.
What is Data Backup?
Backup is an independent data copy, which saves data within the whole system at a specific point in time. It exists to guarantee high data integrity and recoverability, making sure when the original production data become unavailable due to hardware failure, system corruption, or severe file loss, you can still reverse the situation by restoring the backups.
Backup data can be stored in different media for the 3-2-1 backup rule compliance. For example, besides having them in on-premises physical servers, you can also choose to keep extra copies at remote site, on tape, or on cloud. In this way, any damage to your primary site won’t be able to cause you to panic.
Backup jobs are usually scheduled to run daily, weekly, or monthly, and the time for it to complete depends on both the data volume and transmission methods. Typically, the larger the data volume is, the longer backup time it takes, and sometimes it can take up to hours. Therefore, companies usually won’t choose to backup data during business hours if they use LAN transmission, for it will severely lag the production network performance while slowing down the backup speed. Or, you can just directly choose LAN-Free backup (no bandwidth usage) to transfer the same amount of data in a relatively shorter period of time, if the backup tool you’re using offers such an option.
What is Data Replication?
As we have mentioned above, data replication is also a type of data copy, but what makes it different from backup is that it changes along with the original data—just like you and your shadow. Data replicas are usually stored in offsite secondary storage, which can be written by either synchronous replication or asynchronous replication.
Synchronous replication means replication in real time. Whenever the production data changes, data replicas will also immediately be updated. So that in case key services in the primary production environment shuts down due to hardware failure, they can be immediately taken over by the “shadow” production system.
Asynchronous replication, on the contrary, is to replicate data NOT in real time. Data replicas will usually be kept in the primary storage first, and then the transmission will run by a certain schedule, just like backup, so that there’ll always be a time gap between the actual production data changes and replicas stored in secondary storage. Compared with synchronous replication, it’s more like a way to create data redundancy. It’s still workable as a high availability solution, but there might be a loss of some newly written data.
What're the Major Differences Between Backup and Replication?
Both data backup and data replication are important elements in a complete disaster recovery plan, which closely relate to RTOs and RPOs, the two essential metrics that define the real capability of your plan. Their major differences lie in the protection purposes and dependency level on original data.
Backup is to minimize the loss of your mission-critical data in every possible way. It saves history data status independently from original production data, which focuses more on reducing RPOs (Recovery Point Objectives), making sure you always have recoverable data resources with most files contained. By saving extra copies in different locations and media, you can enjoy absolute data security.
Replication focuses more on reducing RTOs (Recovery Time Objectives), which means to ensure zero downtime in emergency scenarios by helping you build a failover architecture with shadow systems. However, replication is highly dependent on the original data, and it’s rarely possible for it to save you from danger if the original ones are mistakenly deleted or affected by ransomware.
In most work cases, backup is a must-have for companies to ensure the safety and stability of the entire IT environment, while data replication is usually implemented on key applications and databases for zero downtime guarantees. You can take both business needs and budgets into consideration when setting up your own BCDR architecture, and have this one always in mind: backup is the most important friend you can’t abandon no matter what happens.
This blog introduces the concepts of data backup and data replication, along with their major differences and key use in disaster recovery scenarios. They’re complementary components and reduce PROs and RTOs in their own way.
A good backup solution should be able to help you reduce RPOs and RTOs at the same time. Vinchin Backup & Recovery offers smart backup scheduling and instant restore for virtual environments to help you improve backup frequency of the entire system, and uptime of key applications. Download the 60-day full-featured free trial to explore them in person.