A bit more science...
I threw three different surface scans at a 25Gb partition on my Early 2009 White MacBook/2.0GHz Core 2 Duo/1.07 GHz Bus Speed:
- TechTool Deluxe
(Sample per Terminal>top) Surface Scan > %CPU=9.5% > Time=0:01.66
c. 470 sec
- sudo dd if=/dev/rdisk0s2 of=/dev/null conv=noerror bs=10240000
(Sample...) dd > 0.9% > 0:00.42
26730483712 bytes transferred in 438.868714 secs (60907699 bytes/sec)
- sudo dd if=/dev/rdisk0s2 of=/dev/null conv=noerror
(Sample...) dd > 25.4% > 0:12.57
3820858880 bytes transferred in 1473.733713 secs (2592639 bytes/sec)
I note that example 3, which was not run to completion, extrapolates to 10,310.14488 secs (171.835776 minutes) for the full 25Gb, close to a staggering 29 hours for my entire 250Gb HD, and that my HD temperature was the highest I've ever seen it while it was running.
I dunno... It seems to me that 29 hours is an extraordinarily long time and, too, that running for that long a period of time at a relatively very high temperature is likely to be detrimental to an HD.
Anybody?
And can anybody explain why TechTool Deluxe's "surface scan" is so much faster than "dd?"
