On 11/23/06, Tobias Hahn <[EMAIL PROTECTED]> wrote:
On OSX, you have two types of disk images, dmg and sparseimage. If
you create a dmg of a certain size, the imagefile takes up that much
space, regardless of how much data it contains. If you create a
sparseimage, the imagefile originally takes up much less and grows as
needed. hdiutil compact reclaims wasted space in sparseimages. Look
at the following example:
$ hdiutil create -size 5m my.dmg
$ hdiutil create -size 5m my.sparseimage
$ ls -l my.*
Now you can do stuff like
$ hdiutil create -size 100t huge.sparseimage
even if you only have a physical hd of just 0.1g. Maybe on 64bits,
you can also try
$ hdiutil create -size 1e gigantic.sparseimage
(on my machine, this fails. 1e = 2^60 = 1.2 * 10^18)
Now do
$ ls -l *.sparseimage
Pretty cool, eh? Does that help explain the term "sparse"?
Cool, thanks!
~ Nathan
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