From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932604AbWHDLle (ORCPT ); Fri, 4 Aug 2006 07:41:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932605AbWHDLld (ORCPT ); Fri, 4 Aug 2006 07:41:33 -0400 Received: from nsm.pl ([195.34.211.229]:34058 "EHLO nsm.pl") by vger.kernel.org with ESMTP id S932604AbWHDLld (ORCPT ); Fri, 4 Aug 2006 07:41:33 -0400 Date: Fri, 4 Aug 2006 13:41:25 +0200 From: Tomasz Torcz To: linux-kernel@vger.kernel.org Subject: Re: Checksumming blocks? [was Re: the " 'official' point of view" expressed by kernelnewbies.org regarding reiser4 inclusion] Message-ID: <20060804114125.GA10814@irc.pl> Mail-Followup-To: linux-kernel@vger.kernel.org References: <200607312314.37863.bernd-schubert@gmx.de> <200608011428.k71ESIuv007094@laptop13.inf.utfsm.cl> <20060801165234.9448cb6f.reiser4@blinkenlights.ch> <1154446189.15540.43.camel@localhost.localdomain> <44CF84F0.8080303@slaphack.com> <1154452770.15540.65.camel@localhost.localdomain> <44CF9217.6040609@slaphack.com> <20060803135811.GA7431@merlin.emma.line.org> <44D285DF.7060905@elegant-software.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="AhhlLboLdkugWU4S" Content-Disposition: inline In-Reply-To: <44D285DF.7060905@elegant-software.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --AhhlLboLdkugWU4S Content-Type: text/plain; charset=iso-8859-2 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Aug 03, 2006 at 07:25:19PM -0400, Russell Leighton wrote: >=20 > If the software (filesystem like ZFS or database like Berkeley DB) =20 > finds a mismatch for a checksum on a block read, then what? >=20 > Is there a recovery mechanism, or do you just be happy you know there is= =20 > a problem (and go to backup)? ZFS readsthis block again from different mirror, and if checksum is right -- returns good data to userspace and rewrites failed block with good data. Note, that there could be multiple mirrors, either physically (like RAID1) or logically (blocks could be mirrored on different areas of the same disk; some files can be protected with multiple mirrors, some left unprotected without mirrors). --=20 Tomasz Torcz To co nierealne -- tutaj jest normalne. zdzichu@irc.-nie.spam-.pl Ziomale na =BFycie maj=B1 tu patenty spe= cjalne. --AhhlLboLdkugWU4S Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) Comment: gpg --search-keys Tomasz Torcz iD8DBQFE0zJlThhlKowQALQRAk57AKClX8ImQo/m9pvJMdQAhe5nhLMBZgCgzXBd 1DZZ5DjgPTisaa//iQWI/E0= =8u98 -----END PGP SIGNATURE----- --AhhlLboLdkugWU4S--