Curious minds want to know...

I have a 5 GB disk image file I'm backing up.
Actually, it's a "Sparse Disk Image Bundle" consisting of 560+ "bands" each of which is an 8.4 MB file.

I notice when I write to/modify the mounted disk image, the Date Modified for some -- but not all -- of the individual band files change.

When backing up, does QRecall treat each of the bands as individual files even though at the higher level the OS (like Finder) treats the conglomeration as a single file?

If I write to the mounted disk image resulting in say 100 out of 560 of the band files being changed, will QRecall only recapture the changed band files as opposed to the entire bundle?

Steven J Gold wrote:Curious minds want to know...

This is why I love my customers.

I have a 5 GB disk image file I'm backing up.
Actually, it's a "Sparse Disk Image Bundle" consisting of 560+ "bands" each of which is an 8.4 MB file.

I notice when I write to/modify the mounted disk image, the Date Modified for some -- but not all -- of the individual band files change.

Correct. A disk image is a file that pretends the be the blocks of a volume. If the package is broken up into individual files, only the files that correspond to blocks you changed on the "volume" get modified.

When backing up, does QRecall treat each of the bands as individual files even though at the higher level the OS (like Finder) treats the conglomeration as a single file?

Technically, it depends on how you backup up the disk image. If you capture the disk image file/package then QRecall sees them as regular files. If you capture the volume of the mounted disk image, QRecall capture those individual files as it would the files on any volume.

But it doesn't matter (at least to the size of the archive).

QRecall performs block-level de-duplication of the data, so it actually doesn't matter if the disk image is a single massive file, a collection of "bands," or the individual files stored on that disk image. Every file will be broken down into its individual data blocks and analyzed one at a time.

If I write to the mounted disk image resulting in say 100 out of 560 of the band files being changed, will QRecall only recapture the changed band files as opposed to the entire bundle?

Also correct. The advantage of using a disk image with individual bands is that QRecall can skip the analysis of the bands it knows have not changed. But in the end, it doesn't matter how many "bands" you have or which ones were modified, only the modified data blocks get captured.