Quite a few people have been asking me recently how I do my backups, either because they are geeky enough to want to know another geek’s opinion, or because they simply have no idea where to start. So here is my view on making backups and a little insight into my backup strategy.
A bit of “theory”
The reason for making backups should be obvious to all, but apparently it isn’t so here is a little reality check. Let me put it simple: unless you have your data at least twice, you don’t “have” it at all. Whatever media you use to store your data on, it is not a question of “if” that data will ever be lost, but the question “when” it will. If a hard drive dies and you permanently lose some data, it’s your fault, not the disk manufacturer’s or anybody else’s.
Do realize that “backing up” your data to CD or DVD and then deleting the data from your hard drive does not count as properly backing up. You need to have every data twice!
So I need two versions of all my data?
Theoretically, yes. Having your data twice protects you against any of these 2 versions getting lost. In practice though, your main data storage (your pc or notebook) and your backup (your external drive) will often be in the same place together (your house, flat, office, studio). This means that you only need one flood, fire, thief or other disaster to destroy all your versions.
So, to cut to the point you better make sure you also have a second off-site-backup at a different location.
So if I backup I can retrieve any of my data I ever had?
Most backup solutions don’t offer backup versioning. To put this in human terms, this means that you can only go back in time to the last backup you made, nothing before that. Every backup in these cases overwrites the previous backup. There are backup solutions though that offer versioning like Subversion, CVS and the Apple Time Machine software.
The problem of versioning backups is that they tend to grow quickly when your data changes a lot. This is because every change is saved. In other words: if you download loads of videos per week and watch them the same week and trow them away, your disk space might stay constant but your backup will grow fast as it is saving all those videos. Versioning is often only used on very small (but important) data like documents because these sizes tend to be manageable.
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