Bad Blocks... Should I RMA?
rsmith at xs4all.nl
Mon Nov 16 18:24:08 UTC 2009
On Sun, Nov 15, 2009 at 04:06:55PM -0800, Ronald F. Guilmette wrote:
> In one of my systems, I've got a Seagate SATA 500GB drive (ST3500320AS)
> which is actually not very old... purchased 12/11/2008.
> same single block. Here's the relevant lines from /var/log/messages:
> Nov 15 15:24:17 coredump kernel: ad4: FAILURE - READ_DMA status=51<READY,DSC,ERROR> error=40<UNCORRECTABLE> LBA=256230591
> Nov 15 15:24:43 coredump kernel: ad4: FAILURE - READ_DMA status=51<READY,DSC,ERROR> error=40<UNCORRECTABLE> LBA=256230591
> Nov 15 15:24:46 coredump kernel: ad4: FAILURE - READ_DMA status=51<READY,DSC,ERROR> error=40<UNCORRECTABLE> LBA=256230591
> (Don't be confused... The name of the host system here is "coredump"... my
> lame attempt at humor.)
Install the smartmontools port, and check the drive with
'smartctl -a /dev/ad4'. If you see a non-zero Reallocated_Sector_Ct, RMA it
immediately, as it is about to fail. If see other errors reported, RMA it.
(S)ATA disk have spare sectors available. If a sector fails, it is replaced by
one of the spares by the firmware. If you see a non-zero
Reallocated_Sector_Ct, it means that the drive has run out of spares. This is
> P.S. If I _do_ end up RMA'ing the thing back, do I need to worry about
> scrubing the drive squeaky clean first... you know... using one of these
> multiple write-over progs (like `wipe') if I am paranoid... as I am...
> about the possibility of old credit card numbers lying around in unallocated
> sectors on the drive? (The drive is empty _now_, but earlier it was in
> serious/heavy use.)
No. Just fill it with zeros. There was a paper presented at Usenix 1996 that
you could potentially read erased data from the sidebands. But that was
looking at disks make in the early nineties using MFM and RLL encoding. The
encoding on todays disks is very different. The author of te original paper
thinks it is almost impossible to recover overwritten data on a current
harddisk. To quote from the epilogue from
Any modern drive will most likely be a hopeless task, what with
ultra-high densities and use of perpendicular recording...
> I guess what I'm asking is: Do Segate and the other manufacturers care
> enough about their customer's privacy to securely wipe old drives/platters
> that come in to them for RMA? Or do I need to worry 'bout that for my own
I would always wipe them myself. You cannot guarantee that the manufacturer
will do it. But I was under the impression that the information on a platter
can only be properly read by the same arm/head it was written with.
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