I'm attempting to zero a disk on my Mac OS X machine. I'm going for complete zeros and unformatted, so I think of dd. Unfortunately the maximum throughput I've managed to get out of dd is 7MB/s. Just for grins I tried disk utility and it has a throughput of 19MB/s. What gives? I've tried changing the bs option on dd to all sorts of values, but it still hovers around 7MB/s. Why is disk utility so much faster?


That sounds pretty slow for dd, what was the infile you were using? I prefer dd to Disk Utility.app just because it's faster and I find it's easier to work with. The command you should use is:

dd if=/dev/zero of=/dev/[blockdevice] bs=1M

  • I used that exact command, but the throughput stayed at about 7MB/s while Disk Utility was roughly 3 times that. What gives?? – jdizzle May 20 '10 at 0:06

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