In today's world, data is often the most valuable asset possessed by a business, and any significant data loss incident can have devastating consequences as illustrated by a large number of high-profile ransomware attacks that have been sweeping the globe and affecting businesses and organizations of all sizes.
Choosing the right data backup strategy can be the difference between successful recovery and failure. While most modern businesses back up their data, one-third has experienced problems with backup restoration, according to Kroll Ontrack research which surveyed nearly 600 IT administrators.
Your data backup strategy should reflect your needs, budget, and IT resources. Some backup strategies may look good on paper, but, unless they align with your business, they may be more trouble than they’re worth.
Full backup is the simplest data backup strategy. As the name suggests, it involves a copy of all stored data. If you would like to create a full backup at the end of each work day, you would need at least 5-times the amount of backup space as you have storage space. The high storage space cost is the biggest disadvantage of full backups. Another major disadvantage is the long time it takes to create a backup. It doesn’t matter how many changes have occurred since the last backup; a full backup will always include a copy of every stored file even if all of them have already been included in a previous backup.
These disadvantages are somewhat outweighed by fast restore times and excellent reliability. With multiple full backups, each backup is usable on its own even though it may not entirely reflect the current state of data. Since everything is stored in a single location, the restoration process is fast and hassle-free.
When dealing with large data sets, it’s often unfeasible to always create full backups. It makes much more sense to create a single initial full backup and then back up only files that are either new or that have been changed since the last backup. The incremental backup strategy does precisely this. For example, a full backup copy is created on Monday. Tuesday’s backup then contains only new or changed data since Monday, and Wednesday’s backup contains only new or changed data since Tuesday.
The resulting backups are much smaller than full backups, and it takes just a short while to create them, depending on how many files there are to back up. On the flip side, the restoration process can be more time-consuming since it’s necessary to move from the initial full backup through several incremental backups all the way to the last backup. This also means that the entire backup chain is only as strong as the weakest link. Regular integrity checks are necessary, and multiple copies of each incremental backup are often stored at different locations.
Some backup solutions can consolidate the data from the latest full backup and any subsequent incremental backups into one archive file, creating what is known as a synthetic incremental backup. This backup method combines the advantages of full backups with the advantages of incremental backups. Synthetic incremental backups don’t take long to create and can be recovered very quickly.
When all incremental backups are stored on either a large disk array or in a tape library, we talk about incremental-forever backups. Even though these backups are really just large collections of individual incremental backups, they behave as if they were full backups.
Just like incremental backups, differential backups also start with a full backup. The difference is that a differential backup always contains all new or modified data since the full backup. A differential backup from Wednesday will contain changes from Tuesday and Wednesday, and a differential backup from Friday will contain changes from Tuesday, Wednesday, Thursday, and Friday.
The advantage is a differential backup never requires more than two backup data sets—the initial full backup and the subsequent cumulative backup. This means faster recovery times and fewer backups to manage. The storage space requirements are higher compared to incremental backups, but not as high as with full backups.
Your backup strategy should reflect your recovery objectives and business needs. Don’t forget that it’s important also to consider the storage location of your backups. Having all eggs in one basket is a recipe for disaster. Modern cloud backup solutions allow you to easily spread your backups across different geographic regions without any overhead.