On 2012-12-10 07:35, Timothy Coalson wrote:
    The corrupted area looks like a series of "0xFC 0x42" bytes about
    half a kilobyte long, followed by zero bytes to the end of sector.
    Start of this area is not aligned to a multiple of 512 bytes.

Just a guess, but that might be how the sectors were when the drive came
from the manufacturer, rather than filled with zeros (a test pattern
while checking for bad sectors).  As for why some other sectors did show
zeros in your other results, perhaps those sectors got reallocated from
the reserved sectors after whatever caused your problems, which may not
have been written to during the manufacturer test.

Thanks for the idea. I also figured it might be some test pattern
or maybe some sort of "secure wipe", and HDD's relocation to spare
sectors might be a reasonable scenario for such an error creeping
into an LBA which previously had valid data - i.e. the disk tried
to salvage as much of a newly corrupted sector as it could...

I dismissed it because several HDDs had the error at same offsets,
and some of them had the same contents of the corrupted sectors;
how-ever identical the disks might be, this is just too much of a
coincidence for disk-internal hardware relocation to be The reason.

Controller going haywire - that is possible, given that this box
was off until recently repaired due to broken cooling, and this
is the nearest "centralized" SPOF location common to all disks
(with overheated CPU, non-ECC RAM and the software further along
the road). I am not sure which one of these *couldn't* issue
(or be interpreted to issue) a number of weird identical writes
to different disks at same offsets.

Everyone is a suspect :(

//Jim Klimov

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