Date: Thu, 27 Aug 2009 06:25:49 +0200 From: Roland Smith <rsmith@xs4all.nl> To: Polytropon <freebsd@edvax.de> Cc: Kelly Martin <kellymartin@gmail.com>, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: hard disk failure - now what? Message-ID: <20090827042549.GA40011@slackbox.xs4all.nl> In-Reply-To: <20090827010358.121fa496.freebsd@edvax.de> References: <1338880b0908241129p75b6845cg26d21804e118364@mail.gmail.com> <20090824223247.GD43410@slackbox.xs4all.nl> <1338880b0908252246s21191e83k7c251366b706532@mail.gmail.com> <20090826180741.GA23120@slackbox.xs4all.nl> <20090827010358.121fa496.freebsd@edvax.de>
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--7JfCtLOvnd9MIVvH Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Aug 27, 2009 at 01:03:58AM +0200, Polytropon wrote: > On Wed, 26 Aug 2009 20:07:41 +0200, Roland Smith <rsmith@xs4all.nl> wrote: > > If the drive is that bad, it is doubtfull if dd or ddrescue will be abl= e to > > get a good copy. >=20 > There's an additional problem: Let's assume dd creates an 1:1 copy > of the file system in its actual state - nobody guarantees that > this file system is fully intact, or can be repaired. Certainly. If filesystem data is missing, there is only so much that fsck_u= fs can do about it. =20 > > Using dd you make a block-for block copy; dd doesn't know about filesys= tems. > > You could pipe the output from dd through a compression program like gz= ip or > > bzip2. That could yield a smaller image. But you'd have to uncompress i= t in > > order to use it. >=20 > I'm often told that hard disks are cheap today, and it's much > more relaxing operating on a plain image than on a compressed > one. Of course. But if you are operating under restricted scape constraints... > > I hope you get a good copy, but it doesn't sound too likely. I'm not a > > hardware expert, but if the disk is really breaking down in the hardware > > or electronics, it is not inconceivable that even reading might further > > deteriorate it. >=20 > In case of such hardware defects that causes growing problems, > it's wise to get the data (1st) as fast as possible and (2nd) > as accurate as possible - before the disk completely dies. And (3rd) in as few tries as possible! > In such a case, it's still possible to recover data, e. g. to > mount the disks (the cylinders or platters) into another drive > unit. But if the disks are defective theirselves... I wonder if that is still possible with current drives? My impression was (from a paper that I can't locate ATM) that data densities are so high that= it is extremely difficult to read the data with different arm/head assembly th= en the one it was written with. > > Time to start thinking about a solid backup strategy as well. :-) >=20 > The correct time to do so is BEFORE you start storing data. :-) Very true! But since the lack of backups was what got the OP in this mess in the first place... 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) --7JfCtLOvnd9MIVvH Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.12 (FreeBSD) iEYEARECAAYFAkqWCs0ACgkQEnfvsMMhpyWNkwCeKyGm6yvip+Djw4FKd6ZCd94f 4HQAmwciictGaiEDceKFmIAB8tS0c5s/ =nm7g -----END PGP SIGNATURE----- --7JfCtLOvnd9MIVvH--
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