On Fri, Dec 17, 2004 at 10:05:15AM -0500, gslink wrote: > The problem with bad sectors is not with sectors that show a write check > but with those that don't show a write check but are bad. The write There is no way to detect disk errors of this form. Nor do we need to because the drive will do sparing for us > check on most hard drives is very simple and consists only of parity. Wrong. The check on any modern drive is built around very complex mathematics because the bit density is so high that the data is always full of errors. Advanced FEC algorithms are used which can not only analyse the data and recover it from the noise but also assess how close to unreadable the block is and can then rewrite the block and if that fails move it. IDE disks also pretty much ignore "format" and "verify" commands except for reading each disk sector and checking if it seems acceptable. If most of the disks you get have bad spots find a proper supplier. I've only seen that occur when people are not shipping drives properly (so the get damaged in transit) or if the vendor is recycling RMA'd drive pulls on the quiet. Out of the box drives don't come with errors and haven't seen the days of EIDE. Alan