View Full Version : Erasning x-drive, space for other files?

07-19-2007, 05:59 PM
Good day everyone,

My question is the following:

If i go ahead and make a backup all files,
SD will erase everything on my external drive,

then will it be possible later on after the backup
(and will there be space) to save other files to this external disk?
Or does SD kind of "occupy" the whole of my x-drive?

(Can't see this happening, but just in case )

bw, Omar K N

07-20-2007, 03:27 AM
If you do not need your backup to be bootable, you can get away with backing up to a disk image on your external drive. If you have the space, you can even have multiple of these backup disk images. Also, a backup to a disk image will probably be slower than a backup to an actual partition (since it has to go through the filesystem and disk layers twice: once for the filesystem of the image itself, and once for the filesystem the image file is store in). If you backup to an image, you can store other files along side your image(s) without any problems from SuperDuper!.

If, however, you want your backup to be bootable, it must be on its own partition. If your external disk is large enough, you can divide it into a partition for your backup and a partition for your other data storage. You would use Disk Utility to accomplish this.

In addition, if you want your backup to be reliably bootable and/or reliably restorable, you should only ever use the Erase, then copy or Smart Update options with Backup - all files selected. Technically, what you seem to want to do is possible, but you will likely end up sacrificing the ability to boot from your backup and probably also the ability to restore from the backup, too.

When you store your system backup and other data files together, you can not use Erase, then copy or Smart Update, since those copy methods would delete any files that are not actually on your system drive. Using Copy different or Copy newer would allow you to keep other files in the same partition/image with your system backup, BUT, over time the system backup would be corrupted since normal OS updates and other software updates often delete files that these copy methods would leave behind. The result would be a merged collection of all the files that were ever on your system at the times you made your backups. This might sound desirable, but having those extra, old files around could easily result in an unbootable or an unusable-after-restore backup.

My Bottom Line Suggestion: If your external disk is much larger than your system partition/disk, then partition your external disk into one partition that is the same size as your system partition/disk, and put the rest of the space in another partition. If you commonly modify very large files, you may want to make your backup partition a bit larger than your system partition (it can help avoid a potential out-of-space issue when SD! copies the new file over before deleting the old file). Use Backup - all files and Smart Update (or Erase, then copy if you are not a registered user) to do your backup to the first partition of your external disk. Store other files on the other partition. You may even consider making two or more system-sized partitions on your external disk and rotating backups among them to give your a farther restorable "horizon".

Note: If you are storing files on the external disk that you do not have copies of elsewhere, they are not safe. You backup drive could die, just like your internal drive could. Never store critical data in only one place.

(just a customer, I speak neither for Shirt Pocket nor for Dave Nanian)

07-20-2007, 08:51 AM
Note, in addition to what Chris says, that there's an entire section of the User's Guide dedicated to this -- "Storing a backup alongside other files on a destination drive" -- so take a look there.

07-21-2007, 05:50 AM
Thank you all very much for this essential information,
and also where to find it !

I'll save this file for later .

bw, Omar K Neusser