SD does not erase sparseimage
 

Hi,

I use DS to backup my "VM" drive where I keep my Parallels Virtual Machine Images on. Those files are like 10-15 GB's in size, so I did NOT choose to use "Smart update" because most of the times ALL files changed and needs to be backuped.

Instead I use "Erase ..., than copy file" from the "During copy" drop-down.

Strange thing is, the sparseimage is 221GB, while, when I open the sparseimage, the only folder in the sparseimage is only 55GB.

Does this mean that SD does NOT erased my sparseimage, but instead "deleted" the files IN the sparseimage and writes the newer files into the sparseimage, so that the sparseimage gets bigger and bigger?

Problem is that my backup HD gets full and my next backup fails because it runs out of space.

Thanks

Patrick Mast
http://www.PatrickMast.com

As you can read in other threads, that's the way OSX handles images, Patrick. And, yes -- we "erase" the contents of the image, and OSX doesn't shrink it.

If you can't write directly to the drive (which would avoid this problem), perhaps you can write a little AppleScript to delete the image before the backup, and schedule that using an iCal alarm?

Why can't SD not just Delete the image, and than start to copy? The info SAYS it's going to to just THAT :)

From the "During copy" dropdown:
"Erase ..., than copy files from..."

Patrick

Because the "erase" refers to the volume, not the file.

So, same question. Why does SD not simply remove the FILE? ;-)

Patrick
http://www.PatrickMast.com

Because it doesn't: erasing the contents of the file make more sense most of the time, because then the volume doesn't have to be re-extended.

Take a look at this page, it shows you how to compact (shrink) your sparse image.

What is "re-extending" a volume.

I'm still convinced that, deleting the parse-image file is the more simple solution. Ok, so, lets get a compromise here ;-)

Why not have an extra checkbox in the "Before copy" section with "Erase parse-image"?

Patrick

A sparse image starts out small, and extends as it grows. It takes time and I/O to extend its size -- an image that's already a bit "fat" is faster.

I tend to frown on checkboxes that would be rarely used, like this one, and whose benefit is not immediately apparent to most users...

Like the OP, I sure would use it and consider such a feature to be a helpful addition.