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hi, i have a similar question i'd love to find an answer for... if i have a large file that's stored on a sparse bundle disk image, and i make a small change to that file, will every part of the bundle ("band" i guess it's called) that contains this file be changed and need to be rewritten? or just the few bands that actually had new data written to them?
to be specific, i use thunderbird for e-mail, which stores all my mail in one giant text file. so every time i get a new e-mail appended to it, i have to re-write several hundred megabytes to the backup. what if i stored my thunderbird mail folder on a sparse bundle? would it then back up only the small part of the mail file that changed? or every part of the bundle that contained part of the mailbox file? if someone's already tried this, it sure would save me a lot of "experimenting" time...
i know i could avoid this by switching to apple's mail.app, or by sorting all my mail into subfolders, but i just don't have time. i use superduper because i want something fast i can really rely on without a lot of fussing around.
one more thing that i'd really like to find out, is whether superduper backs up sparse bundles while they are open and mounted, and if so, whether that is safe? in researching how time machine works, i found that it won't back up your filevault-protected home folder (just a big sparse bundle) unless you're logged out and the image is unmounted. however, it seems that it will happily back up mounted sparse bundles you've created yourself with disk utility, if you're not using filevault. this seems like a contradiction - and another reason i don't trust time machine. does superduper back up open/mounted sparse bundle disk images? is that really safe? wouldn't the image become corrupted, if you backed up only some parts/bands just before an adjacent part was changed?
in the past i've never bothered unmounting disk images, and closing all other open files/programs before doing a superduper backup in the background. but switching to this new file format - which will be great if it works - i'm worried that's no longer good practice. again, it would save me a lot of time and guessing, if someone has an informed answer about this, 'cause i've spent half the day searching support sites and blogs, and still don't feel confident that my backup strategy remains reliable.
thanks...
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