Backing up to a .DMG File on Server

[Marco_Polo]

I'm very frustrated over this.

How do I get SD to make automated backups onto an ordinary disk image file that's situated on a remote server?

Alternatively, how can I make SD wait nicely for the image file to be mounted when I use AppleScript? SD does not respect delays coded in the CopyJob.applescript file.

Details...

Due to issues with ever-growing .sparseimage files filling up my server, I decided to make regular backups to an ordinary .dmg file instead. The .dmg file is the same size as my hard drive and resides on a server volume.

SuperDuper won't mount the .dmg file for scheduled backups.

It won't do it from a scheduled backup when I select the .dmg file as the target in the main window and it won't do it from a scheduled backup when I select the mounted volume from the .dmg file as the target.

I thought that I'd just work around this problem using AppleScript to mount the server and disk image before the backup is run. I altered the CopyJob.applescript file. My first attempt looked like this...

on beforeRunningCopy()
tell application "Finder"
	mount volume "smb://192.168.n.n/BACKUP_VOLUME"
	open file "BACKUP_VOLUME:Backup.dmg"
end tell
end beforeRunningCopy

But SuperDuper's scheduled backup failed with this error:
The automatic copy aborted because SuperDuper! could not locate the Destination volume

It looked for the volume before it was mounted.

I figured that I could work around this problem with a delay to check for the existence of the mounted volume, so I revised my code...

on beforeRunningCopy()
tell application "Finder"
	mount volume "smb://192.168.n.n/BACKUP_VOLUME"
	open file "BACKUP_VOLUME:Backup.dmg"
set i to 0
repeat until (i = 1000)
     if not (exists "Boot HD:Volumes:Backup") then
          delay 15
          set i to 0
     else
          set i to 1000
          delay 30
     end if
end repeat
end tell
end beforeRunningCopy

SuperDuper's scheduled backup failed with the same error!

Watching it while it worked, I could see that SuperDuper completely ignored the delays in the AppleScript. It started the script going and then tried to find the volume right away without waiting for the script to complete.

How can I get SD to mount the disk image and WAIT for it to completely mount before starting the backup?