A Treasure Trove of Crap?
Applications, especially browsers, make extensive use of caches: folders that are full of zillions1 of files that make re-accessing data, especially network data, faster after the first time.
They’re typically considered disposable, temporary, and transient, since the content can be re-downloaded (or regenerated) later.
Sounds Perfect For a Skip!
Given the sheer quantity of this stuff, you’d think I’d configure SuperDuper’s copy rules to skip it. It’d certainly make some kinds of copies faster, and the copy itself smaller.
Case closed!
Not So Fast
But…I don’t, even though it would be easy. And there are a couple of reasons for that.
First: if you’ve got a bootable backup, it’s more likely to perform the way you want in the event you need to get to work ASAP if the cached information is retained. You don’t have to rebuild/redownload the info: once booted, things are available just like they were on the original drive.
Second: in the event of a disaster, I want to maximize the likelihood that you’ll be able to recover your data.
If you’ve had some sort of disaster, or hardware failure, or you’re doing data reconstruction, the data you need may be both where it was originally, and in a cache somewhere else on the drive.2
Copying the caches may take a little extra time and space, but if it proves useful in the event of a problem, it’s well worth it.
(And if you disagree, you can, of course, create rules that exclude anything you’d like.)3
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A zillion is, of course, one-one-hundreth of a bazillion. ↩︎
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I’ve considered copying /tmp (/private/tmp) for similar reasons…but do copy individual application temporary folders. ↩︎
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The rule pattern ** can be useful here. For example,
/Users/*/Library/**/Cacheswill exclude any folder named Caches in any User folder under Library, regardless of depth. ⌥ Option lets you edit the rule to enter an arbitrary pattern.
Be careful, though: use Preview to check the effect of your rule. And I suggest including “Backup - all files”, so you start with the built-in SuperDuper rule. ↩︎