Date: Mon, 16 Nov 2009 19:23:58 +0100 From: Roland Smith <rsmith@xs4all.nl> To: "Ronald F. Guilmette" <rfg@tristatelogic.com> Cc: freebsd-questions@freebsd.org Subject: Re: Bad Blocks... Should I RMA? Message-ID: <20091116182358.GA95918@slackbox.xs4all.nl> In-Reply-To: <42307.1258330015@tristatelogic.com> References: <42307.1258330015@tristatelogic.com>
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--bp/iNruPH9dso1Pn Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Nov 15, 2009 at 04:06:55PM -0800, Ronald F. Guilmette wrote: >=20 > In one of my systems, I've got a Seagate SATA 500GB drive (ST3500320AS) > which is actually not very old... purchased 12/11/2008. <snip> > same single block. Here's the relevant lines from /var/log/messages: >=20 > Nov 15 15:24:17 coredump kernel: ad4: FAILURE - READ_DMA status=3D51<READ= Y,DSC,ERROR> error=3D40<UNCORRECTABLE> LBA=3D256230591 > Nov 15 15:24:43 coredump kernel: ad4: FAILURE - READ_DMA status=3D51<READ= Y,DSC,ERROR> error=3D40<UNCORRECTABLE> LBA=3D256230591 > Nov 15 15:24:46 coredump kernel: ad4: FAILURE - READ_DMA status=3D51<READ= Y,DSC,ERROR> error=3D40<UNCORRECTABLE> LBA=3D256230591 >=20 > (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=20 '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 bad news. > 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 unalloca= ted > 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 [http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html]: 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 > self? 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. Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --bp/iNruPH9dso1Pn Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) iEYEARECAAYFAksBmL4ACgkQEnfvsMMhpyUZAQCfcswnMriwAplITWaMz0LzI22w jtsAnjnucdmrCoHeoM6/5ulkJoLyOz/A =dWDB -----END PGP SIGNATURE----- --bp/iNruPH9dso1Pn--
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