In today’s day and age, the importance of backups cannot be overlooked — especially when you’re in the business of managing your customer’s data, and even more so when you happen to be the one who actually doing the backup checks and monitoring of backup data. If the company you work for already has backup monitoring software, then good for you!
But if not and you’re in charge of backups, and you’re still learning the ins and outs of it, then you’ll need to master the basics. And by basics, I mean realising that there are different strategies when it comes to backing data up. Let’s start with the simplest thing — learning the different backup strategies.
What are full backups?
True to its name, a full backup does just that — it backs your data up in full. No buts or ifs; regardless if parts of your data were unchanged from the last backup, full backups copies all your disk sectors to a backup image file.
As full backups are backing up all disk sectors they will take up a similar amount of space as the source data being backed up. Depending on your backup software, your full backups may leverage data reduction technologies such as compression or deduplication to reduce the size of your full backup.
Given full backups are backing up every disk sector, backup time will be considerably longer than other backup methods that may only update the most recently changed data. When considering your Restore Point Objective (RPO) – or how often you’re taking backups the time of full backups should be taken into consideration.
Full backups are typically your safest option when it comes to data integrity and can often offer faster recovery times when compared to incremental backups due potential risks faced from chaining incremental backup together when backup jobs run, or having to merge incremental backup chains together when performing restorations.
What are Incremental Backups?
Unlike a full backup, an incremental backup only backups up the data that has changed. Each incremental is stored in a “backup chain” with the first backup in the chain typically being a full backup and each subsequent an incremental backup. Of course, most modern backup software will allow you to control the configuration of how often you perform incrementals and fulls. For example you might configure your full backup to be on a Sunday night while all other nightly backups are incrementals.
Incremental backups are not only dramatically faster than a full backup, but they also take a lot less backup storage as you are only storing the data that has changed since the last backup. Much like full backups, they also often benefit from modern data reduction technologies such as compression and deduplication.
For all of their benefits, incremental backups do come with their risks. Most specifically is that if one incremental backup is corrupted then the entire chain following the corrupted incremental will be corrupt and you won’t be able to perform a restoration. Most backup software will however allow you to perform regular health checks on your backup chains to ensure this isn’t an issue but you should consider adding regular full backups into your backup schedule just in case.
And while your Restore Point Objectives (RPO) can be dramatically reduced with incrementals, your Restore Time Objectivices (RPO) may be increased due to the restoration process needing to merge all the incremental backups together before the restoration can actually begin. While there are approaches such as “Reverse Incrementals” like that seen in Veeam’s backup tool, where incremental backups are merged into the full after the backup is taken, only the most recent incremental backup will allow for a quicker restoration.
Ultimately when it comes to backups, understanding the risks with each type of backup is important to building your backup strategy. Some businesses have less appetite for risk and may require more frequent backups (RPO) or may need faster restorations (RTO) to ensure they can meet certain business requirements.
Some backup technologies provide further benefits beyond the traditional backup / restore approach so when designing your backup strategy, understand the risk appetite of the business first and work backwards when finding a suitable solution.