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I'm using KNOPPIX to erase some HDs prior to decommissioning PCs. The command to do this is quite simple:

dd bs=4096 if=/dev/zero of=/dev/hda

(Or maybe /dev/sha, depending on what kind of drive it is.)

When I initially boot KNOPPIX, it seems perfectly responsive. However, after a minute or two of erase activity, the system becomes massively unresponsive. Like, the screen went blank, so I pressed a key to make it come back, and I could actually watch the system drawing the individual characters onto the screen, a few per second.

There's no CD activity while this happens, and there's no swap partition defined, so I'm at a loss as to what the hell is taking so long just to display some text.

Similarly, if I press the caps lock key, it takes about 15 seconds for the light on the keyboard to respond. That's an awfully long time, IME.

I'm running at runlevel 2, if that makes any difference.

Does anybody know what's taking so long? (And, ideally, how I can make it not do this.)

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That's not a secure way to erase disks. There's lots of better tools - shred comes as standard in most Linux distros (though I'm not sure about Knoppix). Try running top / sar / vmstat etc before starting the overwrite. –  symcbean Aug 7 '12 at 13:17
    
It's "secure" in that the only way to recover the data is to physically take the disk apart. (The same cannot be said of a simple reformat.) I don't need particularly high security; there's nothing that sensitive on here. –  MathematicalOrchid Aug 7 '12 at 13:47
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2 Answers

up vote 1 down vote accepted

Consider using DBAN instead. You'll get a progress bar.

Why does everybody recommend Dban over more fundamental methods?

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This doesn't actually answer the question I asked. But it's the most useful answer, so I'm going to accept. –  MathematicalOrchid Aug 7 '12 at 13:46
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Does increasing the block size in dd help at all? Try with

dd bs=1M if=/dev/zero of=/dev/hda
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I'll go check... –  MathematicalOrchid Aug 7 '12 at 13:19
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