Date: Wed, 26 Jan 2005 14:58:17 -0800 From: Kris Kennaway <kris@obsecurity.org> To: "Terry R. Friedrichsen" <terry@uplift.hosp.misyshealthcare.com> Cc: freebsd-questions@freebsd.org Subject: Re: FreeBSD 5.3 file system troubles Message-ID: <20050126225817.GA62727@xor.obsecurity.org> In-Reply-To: <200501262253.j0QMrkOJ043661@uplift.hosp.misyshealthcare.com> References: <200501262253.j0QMrkOJ043661@uplift.hosp.misyshealthcare.com>
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--fdj2RfSjLxBAspz7 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jan 26, 2005 at 03:53:46PM -0700, Terry R. Friedrichsen wrote: > I wrote: >=20 > >> try running something that works the file system and simply turn off t= he > >> system power in the middle of it. >=20 > to which kris@obsecurity.org replied: >=20 > > This is expected if you don't turn off write caching of the hard > > disks. It breaks the softupdates consistency model because data > > written to the disk may not actually be written to the disk, so it's > > not there following an unexpected power cycle. Unfortunately write > > caching causes a performance hit, and there was a large user backlash > > when it was briefly enabled by default some years ago. >=20 > What you say is true, but what I'm observing is far worse than simply > missing the last few blocks of output files, etc. >=20 > The last time I had to power-cycle the Alpha box (because Xorg hung it), > it rebooted to single-user mode but I couldn't even run "sh" because > some file in lib was missing. Or if I *do* get into "sh" to run fsck, > it finds *hundreds and hundreds* of problems ... Some disks are also known to go crazy and scribble everywhere when they lose power. Kris --fdj2RfSjLxBAspz7 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (FreeBSD) iD8DBQFB+CCJWry0BWjoQKURAq5/AKC2BfHVi1nMk5pu6OczkdS8tGJ4owCeKcMK crSDx84vc0lAHeOcuFvKo5o= =LuBk -----END PGP SIGNATURE----- --fdj2RfSjLxBAspz7--
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