It's usually good enough, however I've found a number of lower quality USB enclosures that handle things better when setting it as high as 32MB so that as much data is in buffer as possible for them at all times. any higher and I've not seen any speed difference but below 16MB and they'll run at nearly half speed for some reason.
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On OSX, you'd rather change the dd line to the much faster:
There is nothing special about OSX in this case. Just change this to bs=1024 regardless.
You missed it:
1. bs was already included in the post (FWIW the shorthand is '1M' in Linux, and that's 1048576 :-))
2. I was referring to the use of disk vs rdisk (i.e buffered vs unbuffered/raw, see details[0]), which IIRC is a BSD-ism.
Using rdisk gives a tenfold increase in speed here. Without it you're nowhere near USB2 speeds.
[0]: http://lists.apple.com/archives/filesystem-dev/2012/Feb/msg0...
Linux's disk caching is good enough that I haven't been able to observe a difference when I change bs= on Linux. But it certainly won't hurt.
It's usually good enough, however I've found a number of lower quality USB enclosures that handle things better when setting it as high as 32MB so that as much data is in buffer as possible for them at all times. any higher and I've not seen any speed difference but below 16MB and they'll run at nearly half speed for some reason.
Thanks! I'll add this.