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Created September 19, 2015 23:25
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Fast dd in OS X
Raw
gistfile1.txt
seg$ diskutil unmountDisk /dev/disk1
seg$ sudo dd bs=1m if=somefile.iso of=/dev/rdisk1
From man hdiutil:
/dev/rdisk nodes are character-special devices, but are "raw" in the BSD sense and force block-aligned I/O. They are closer to the physical disk than the buffer cache. /dev/disk nodes, on the other hand, are buffered block-special devices and are used primarily by the kernel's filesystem code.
References:
http://daoyuan.li/solution-dd-too-slow-on-mac-os-x/
http://superuser.com/questions/631592/mac-osx-why-is-dev-rdisk-20-times-faster-than-dev-disk
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