After doing my Clean Start I realized that my Time Machine backup drive was running low on space. This really isn't a problem as Time Machine will start to automatically delete older backups to make room for newer ones (also note that 2 computers backup to this drive over the network). The question becomes is that what I really want? After your initial Time Machine backup, Time Machine will continue to make incremental backups of the files that are added or changed until the drive/partition fills up. At that point depending on your prefs it will either ask for more space or automatically make more space by deleting older backups. This means that you can only go as far back as your oldest backup to restore a file. The less space you have on your backup drive the shorter your span will be for going back. Because of the lack of space on my old drive Time Machine had to delete all the backups older than December 17th, 2010.
My weird way of archiving
Let's talk for a moment on the difference between a backup and an archive. A backup is a copy of your hard drive/files so that you can restore them in case something goes wrong. Your drive crashes, you restore from a backup. You acidently delete or corrupt a file, you pull a copy of the file off your backup. However, an archive (in my opinion) is a file that you are done with and probably won't need again, but you want to keep it just in case you do.
Let's say it's an invitation for your 25th Anniversary Party. After the party is over that 25th Anniversary isn't going to ever happen again. Chances are you're not going to ever need that invitation again. Sure you might want to use it as a template for another invitation or you may get a request to print it for it for sentimental value, but the chances of you pulling that file back up again after the party is over are rare! Rather than trash it, you put it on a drive, CD, DVD, thumb drive, etc. "just in case." That's an archive!
I don't archive! Well at least not in the traditional sense that I've described above. I feel that I will either need the file or I won't! Period. If I'll need it again then it's on my main hard drive or file server. If not, I delete it. Sure I have files on my drive that I've forgotten about (that's why I did a clean start), but for the most part the files are there because I'll most likely use them again.
Now let's get back to Time Machine and my new Hitachi 3TB drive – I actually have a "weird" way of archiving via Time Machine. Like I said, the larger the Time Machine hard drive the further back you can go in time. So with my new 3TB drive, backing up my 500GB MacBook Pro drive, I can backup 6 times the amount of data that my drive can hold and keep in mind that it only adds new or changed files to the backup, so that's quite a bit of headroom. This means that if I delete that 25th Anniversary Invite and need it for some reason 3 months later, chances are I can pull it off my Time Machine backup.
Keep in mind that Time Machine isn't going to tell you "hey, I'm about to delete the backup containing that 25th Annversary Invite", so you have no way of really tracking the files this way. Also if your Time Machine hard drive crashes then there goes your archives too. If you NEED an archive, then make an archive. If I delete it, I'm pretty much saying that I won't need it again. However, in case I do I can now reach further back in time and grab it!
You can get the Hitachi 3TB USB 2.0 External Drive here on sale for $170.