The Wonderful World of DMG on Mac
January 12, 2008 //
One of the problems with backing up large number of files is that in addition to the total volume you are copying, the number of files involved has an important impact on the time the process takes. Say, we’re talking about a typical large-volume IMAP folder of 2000 e-mail messages. One such recent mail backup I retain has nearly 60K items in it. That’s a lot of files. I’m not into the tech details but it’s not been hard to figure out that not only finder but also sync utilities like ChronoSync take much time to copy such. Much more time than if we were talking about a single file of the same size.
Year, Mac people need little convincing about the utility and beauty of the DMG concept. (Like many other things about the Mac, there has to be an emotional and subjective part attached to DMGs. Hence the beauty.)
Yet making a DMG file from an existing folder is not so straightforward. One would have wished a context menu item for that. There are many nice utilities. They are quite convenient. However, for some reason, and most probably because I don’t understand their inner workings, I don’t feel entrusting my mail backup in the hands of anyone other than Apple.
Disk Utility is the way to go but need to be aware of a few things.
Firstly, in an un-Mac way, one needs to pre-determine how much space will be required and make a new DMG disk with that size. That’s a fairly time consuming process. Then you copy your files into the new DMG. The real nice thing is once your DMG is ready, you can go back to Disk Utility and compress it.
The above mail back up I mentioned was like 4.7 GB. After compressing I have a wonderfully economical 2.5 GB DMG file instead of the 4.7 GB folder of 60,000 mini files.
Of course you love apple.
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