Date: Thu, 6 Dec 2007 20:22:28 +0100 From: Peter Schuller <peter.schuller@infidyne.com> To: freebsd-questions@freebsd.org Cc: Randy Ramsdell <rramsdell@livedatagroup.com> Subject: Re: Freebsd filesystem ( hard reboot ) Message-ID: <200712062022.36783.peter.schuller@infidyne.com> In-Reply-To: <47581E5E.5080803@livedatagroup.com> References: <4758180C.4060208@livedatagroup.com> <47581D82.5000907@chrononomicon.com> <47581E5E.5080803@livedatagroup.com>
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--nextPart1619892.Zb4A5lHcYH Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline > Well any number of things, but the most recent was a prolonged power > outage. It is important to differentiate between expected fsck activity and=20 unexpected. If you are running without write caching turned on (which is the default), = a=20 power outtage will constitute a crash from which a file system cannot=20 guarantee to recover unless it takes measure to punch through the write cac= he=20 at appropriate moments. If you machine shutdown softly as a result of the UPS communicating that po= wer=20 was running out, you "should" not have to fsck (barring other issues in the= =20 past). fsck need in these cases would indicate a software bug, or a hardwar= e=20 problem. If on the other hand your machine just lost power when the UPS finally died= ,=20 you are relying on luck for recovery if you're on ufs/reiserfs/xfs/etc. Som= e=20 environments will correctly handle this (e.g., ZFS), but most won't. The=20 problem being that drive write caching will prevent the file system from=20 guaranteeing ordering of certain critical operations that must be ordered i= n=20 order to guarantee successfull recovery to a consistent state. That said, you are not supposed to need to answer interactive questions on= =20 boot for all cases of expected inconsistencies. If you are getting prompts = as=20 a result of unexpected inconsistencies, that indicates *something* is wrong. =2D-=20 / Peter Schuller PGP userID: 0xE9758B7D or 'Peter Schuller <peter.schuller@infidyne.com>' Key retrieval: Send an E-Mail to getpgpkey@scode.org E-Mail: peter.schuller@infidyne.com Web: http://www.scode.org --nextPart1619892.Zb4A5lHcYH Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQBHWEv8DNor2+l1i30RAsy3AKDX5LWRsYBzElJ6IiGhhrRnf8F0ewCgtpU+ JawvlkNNXSLvs/wRjNfC4HA= =Lzpn -----END PGP SIGNATURE----- --nextPart1619892.Zb4A5lHcYH--
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