How is Impression's estimate for needed scratch space computed?
The formula that Impression uses to compute necessary scratch space depends on the options chosen for a backup operation, and also on the list of files selected to be backed up. Here's a rundown of the various formulas and when they'd be used:
Using disk images as the backup media:
Scratch space = (estimated total backup size + computed file system overhead based on file count + additional 6% for catalog)
(Enforced minimum scratch size = 10MB)
Using CD/DVD as the backup media (when the largest file can be found):
Scratch space = (CD/DVD disc size + largest file size in backup)
Using CD/DVD as the backup media (when the largest file cannot be found, or when it exceeds 2 x the disc size):
Scratch space = (CD/DVD disc size x 3)
Burning cross-platform compatible, hybrid HFS+/ISO9660/Joliet discs:
Add 1x the disc size to the above calculations
ImpsAnswer 105, last modified: 2006.02.06
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