Backing up to a .DMG File on Server

[Marco_Polo]

Okay, I've found my fix for the other problem, so let's talk about runaway sparse image file growth.

The specific equipment necessary to reproduce the issue as I have experienced it includes a Buffalo NAS, an XFS volume with smb and afp shares and SuperDuper. It doesn't matter whether the remote volume is mounted via afp or smb -- either way, the image files grow until the drive fills up.

The image files don't necessarily grow with every backup. I only observe the results when my backup drive fills up and SuperDuper logs a drive-full error. At that point, perhaps 2-5 times each month, I have a sparse image file that has swelled to be considerably larger than the source. I've gotten into a routine of deleting the over-large sparse image file and starting over when this happens, but it finally got annoying enough that I decided to try something else (the .dmg file solution).

I spoke to Apple engineers during a visit to Cupertino and was told that this is a known problem with sparse image files. Perhaps they misunderstood my question. It seems that you misunderstood me in the earlier thread.