The process of securely overwriting a large disk is a lengthy one; can the process be expedited?
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SuperUser reader John wants to know if there is anyway to speed up the disk wipe he’s performing:
I’ve tried with Disk Utility.app and diskutil at the commandline to zero out a 3TB external USB hard drive, and both work at about 1%/1hr. In Disk Utility.app I am using the 1-pass mode, and with diskutil I am using 1-pass, random.
I’m on Mavericks/10.9.
Is there anyway to for John to speed the process up?
SuperUser contributor Hennes writes:
3TB is a lot of data and USB is both relative slow and has a lot of overhead.
Assuming you have USB 2 and a reasonably good performance of 30-35MB/sec. (this is about the max write speed for USB 2)
30 MB / sec 100 MB per 3 seconds 2000 MB per 60 seconds 2GB per min 120GB per hour, or 25 hours for 3 TB.
That is a long time. And speeds can differ somewhat. In your case it seems four times as slow. Decidedly not fast, but well within reasonably speeds. Especially if there are other USB devices busy on the same USB controller.
There are at least three ways to deal with this:
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