Source drive has total files size increased by ~x4

[msladepas]

My first creation of a external boot copy under Mac OS 10.5.6 had the problem that the SOURCE disk ("Macintosh HD") ended up almost full. I started with Macintosh HD having ~72 GB of files. I ended up with nearly 320 GB on it after the standard recommended path of backup to external FireWire 800 drive: erase target disk, then copy files from Macintosh HD, then "Do Nothing".
Details: this was my work machine, not the laptop I am writing from. It's a Mac Pro 3.2 Intel desktop. I used SuperDuper! 2.5. The target was a LaCie 301832 320GB "Rugged All-Terrain" drive, and, as I said, I used the FireWire 800 interface.
In the end, after deleting a few large files for safety and rebooting, the MacPro was back to ~72 GB on the internal drive (not a RAID drive or anything exotic). However I feel I must have done something wrong since this does not happen when I use SuperDuper! at home (separate license) with my MacBook Pro. It was difficult to come up with a title that conveyed the problem.

[dnanian]

Did you perhaps store the backup -- or a secondary image -- on the original drive?

[msladepas]

Did you perhaps store the backup -- or a secondary image -- on the original drive?

My setup looked just like the attachment. Could that setup put the backup on
the original drive? Keep in mind that I have backed up my MacBook Pro many times with no such problem (running 10.4.11). I would have no idea HOW to store the backup on the original drive, or what a "secondary image" is.

The destination volume had a bootable backup of "Macintosh HD" on it.

As I said, after rebooting, all the "extra" files on the source drive vanished.
It just was disconcerting to unlock the screen and see "you are nearly out of disk space."

[dnanian]

Are you running an AntiVirus program?

[msladepas]

Are you running an AntiVirus program?

On a Mac? whatever for? If I were using a virtual PC, I would use one there.
Anyway, no, I am not running any antivirus software. Symantec Utilites for Macintosh has been shown to be worse than useless. Why do you ask?

Everyone that I have asked about this problem said that it sounded like a (minor) bug in SuperDuper! (minor since the problem went away after a reboot). However, I worry that the next time I use SD!, the source HD will overflow and the backup will fail. Thanks for thinking about this; I was hoping that this was a known problem. I have had no such problem with SD! at home (running 10.4.11 on a 2.4 GHz Intel Core 2 Duo MacBook Pro; boot rom MBP31.0070.B07; 2 GB memory).

[dnanian]

I didn't suggest that you should use an AntiVirus program. I asked whether you were, since AntiVirus programs will take temporary space while copies are being made as they scan the files.

The people who you asked, who pointed at SuperDuper!, are not correct - we do not take temporary space on the source drive while we copy. That's why I'm pointing at other potential areas... perhaps you could run Grand Perspective when the space taken is larger than expected to see what that space actually is?