[[Benjamin]]

It took me a while to work this out, so even if you all know theese procedures by heart, I figured it wont hurt to go over them again:
-Yes, as Gary sais, use a completely separate drive for system & applications, and not only for the reasons already noted, but also so you can freely initialize (format) your audio drive/s when backed up.

For backing up your sessions to CD I find this method safe & sound:
Make sure you've got an empty partition (or a partition from which you've not trashed anything since it was initialized. Open your session, if you're confident that you've got all you want from the session in the playlist, you can safely use the "selected unused" comando, and the "clear selected" commando, but choose REMOVE from session, not delete from disk. If you have playlists that are not used in the session, you may want to get rid of them aswell before running the above procedure. Now, use the "save session copy" command in the file menu (saving audiofiles and all, but not necesarily the root plugin settings, since they can take up quite a lot of space) Save the session copy to the clean partition. Close your session, BUT DON'T SAVE. Open the session copy, check that it's fine, back it up.
For the second backup (or CD backup) I suggest you use the compress files command to get rid of the unused audio in your regions/files. But don't use this command on the original, and don't chuck the original until you've verified that the "compressed copy" is fine. (As you probably already know, this is not data-compression, just getting rid of unused audio)

When initializing/formatting disks, DO NOT USE the low level formatting option. Digi sais no to this aswell. It can reduce life-length on disks. Normally, quick initialize is fine, but if you need to get heavy on a disk, initialize it with apples disktool 1.7.3 or higher, select "zero all data" in the formatting options, but, again, not the low-level format option. You only use low-level formatting if you are changing disk-allocation system (like moving a disk from mac to unix). Then just write new drivers with FWB (3 or higher) for the audio disk/s However, I don't recomend FWB for system/application disks, use the apple utility for that. And a last important note when initializing disks: Don't initialize all the space on a disk, always leave a couple hundred K or more free, in case you need to write a new driver/update your driver without initializing partitions. I tend to leave 2mb or so free, to be safe.

About defragging: Don't, there's no need, and it's a hazardous process. Defragging the system/application volume/s at times can be a good idea, but not the audio-drive/s. If you want optimum performance, you should never delete any files on the volume your working on. Do as I described above for backup, and under normal circumstances you'd be able to carry out a project without running out of workspace anyway, at least if you keep up with your house cleaning duties from time to time. And once you've got the session copies backed up, you can just empty the work-partition - throwing it all in the waste is actually enough, but from time to time it's a good idea to empty all partitions on a disk, and reinitializing it.

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[HYPERSONIC]