March 8, 201511 yr So preclear does not flip the bits on the hard drive, so i made a habit of one'ing out the drive before preclear, so preclear can zero it out. However using this: tr '\0' '\377' < /dev/zero | dd bs=64K of=/dev/sdx On more than one drive maxes out my cpu, and makes the hard drives write at only 44 megs a sec vs 170 megs a sec if its just one. So i just spent the last 30 hours one'ing out a pair of 5 tb drives. I hear badblocks in included with unraid, maybe that would be faster.
March 8, 201511 yr I understand why you're doing this but your reasoning is a little flawed I think. Hard drives don't store individual bits. They use complex codings comprising irregularly spaced changes in magnetic flux to represent combinations of bits. In the old days (about 30 years ago), there was more or less one flux transition on the media per bit of data stored, and the timing of the transition indicated whether the data stream changed from the previous bit or remained the same (MFM encoding). This gradually evolved as disk densities increased so that the more precise timing of a flux transition could represent more than how one bit differed from the previous bit or bits. These days it is much more complex, although derived from similar principles. Some background reading for you... http://www.pcguide.com/ref/hdd/geom/data_PRML.htm Writing ones to the drive before a pre-clear does no harm of course, but there is no guarantee that it will help to find any defects either.
Archived
This topic is now archived and is closed to further replies.