Backup Fundamentals: Why, How, When, and How Often?
It is important to know a little bit about backup, because having great hardware or software just isn’t enough. The best system config is worthless if the backup doesn’t execute properly, if the strategy doesn’t fit to the requirements, or if the restoration process fails. So, let’s start with a few basics.
The answer here should be obvious. If your data is important, then you should be taking all necessary measures to avoid it being modified, damaged, or lost. Various storage media, such as hard disks, optical discs, or flash-based storage, all have their pros and cons, and it doesn’t make much sense to recommend one over the other. However, relying on just one storage medium isn’t a good idea. Ideally, you should have backups of your key data at different locations. All storage media can fail, and we humans tend to modify and delete things accidentally. You just have to plan a bit for the unexpected.
Now we’re getting into the backup fundamentals. It’s important to have recovery data sets in case that your backup fails. You could, for example, be using an external or portable hard drive for regular data backups. This can be done manually if you’re organized enough, or you can utilize a backup program or even create backup scripts. In addition, it makes a lot of sense to plant backups of your key data in an additional location or on another medium, such as recordable DVDs or Internet-based storage. In addition, it’s highly important to work with backups that cannot be modified. DVDs are perfect for this purpose (unless you go for rewriteables), but you could also use affordable hard drives and lock them away in a secure location. In any case, having an offline backup is most important.
Backup can be done for specific data or for your entire system. The latter is typically referred to as a disaster recovery solution if the entire system partition is included. Such a backup comes handy in case of a hard drive failure. After replacing the drive you can recover the entire system volume using the backup software’s boot disc and your backup target (a USB storage device or a network share).
Individual backups can be created in a complete manner, meaning that all selected files get included with the backup set each time the backup is run. Differential backups require a backup solution that supports this feature. It means that only files modified since the last complete backup get copied. And finally there is incremental backup, which also copies only modified files, but refers to the last available backup. This doesn’t have to be a complete backup.
There are different strategies you can follow when doing backups. Incremental backups appear to be economic and reasonable, but it is equally important to balance storage utilization with data provisioning. It’s of little use to create frequent incremental backups with the last, workable full backup created too long ago. I recommend running incremental backups as frequently as possible—depending on the value of your data—and add complete backups on a regular basis. Only overwrite old backups if you’re absolutely sure you don’t need them anymore.
A few words on data security should be added, as data safety isn’t enough. If your files are vital, it makes sense either to put all critical items into an encrypted container, such as TrueCrypt, and put the encrypted file into the backup, or you can use the backup software’s encryption feature. Finally, double-check your backup. Verifying written files makes sense, but you should also take the time and test the restore process. The best backup procedure will be worthless if there are issues during restore.
It doesn’t matter much when you back up unless you have technical or personal constraints. Technically, it may be necessary to execute backups only during suitable windows of downtime. This might be at night when you don’t need your computer or if the amount of data is large enough to have the backup process take hours. For consumers, it makes sense to trigger backups at least once a week if you modify files a lot. This you could do before shutting down your PC in the evening.
To be sure you have enough working restore points, you could rely on daily incremental backups and delete backup sets after a week. An additional, full weekly backup should be archived for a longer time. For example, you could archive the first weekly backup of the month for a longer time. This way should keep you safe but only as long as the archived backups are stored at a safe location or at least not all at the same location.