sparse image vs. sparse bundle

[johncarn]

I thought I understood, but I'm having some troubles.

Enviroment:
Macbook Pro
OS X 10.6.3
NAS appliance running Ubuntu Linux Kernel
USB attached drives

Procedure:
Trying to create a backup on a mapped drive.

I select Disk Image, and use the mapped drive as the location
File type is Read/Write sparse bundle
Option is Smart Update
I hit copy.

I get a message that it could not mount the image, and the logs just show an error.

I try to copy a sparse bundle to the location, but get the same message.

I tried again this morning and selected sparseimage, and the backup is running now, so it looks like using sparseimage would work.

Here is the question. I thought I read (though can't find the post again) that sparse bundle should be used for 10.5 and newer, and would work on network drives, and that sparse image should be used for 10.4 and back.

Can someone offer suggestions or clarify for me?

Thanks.
jc