From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell Leighton Subject: Checksumming blocks? [was Re: the " 'official' point of view" expressed by kernelnewbies.org regarding reiser4 inclusion] Date: Thu, 03 Aug 2006 19:25:19 -0400 Message-ID: <44D285DF.7060905@elegant-software.com> 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> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <20060803135811.GA7431@merlin.emma.line.org> List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Matthias Andree Cc: David Masover , Alan Cox , Adrian Ulrich , "Horst H. von Brand" , bernd-schubert@gmx.de, reiserfs-list@namesys.com, jbglaw@lug-owl.de, clay.barnes@gmail.com, rudy@edsons.demon.nl, ipso@snappymail.ca, reiser@namesys.com, lkml@lpbproductions.com, jeff@garzik.org, tytso@mit.edu, linux-kernel@vger.kernel.org If the software (filesystem like ZFS or database like Berkeley DB) finds a mismatch for a checksum on a block read, then what? Is there a recovery mechanism, or do you just be happy you know there is a problem (and go to backup)? Thx Matthias Andree wrote: >Berkeley DB can, since version 4.1 (IIRC), write checksums (newer >versions document this as SHA1) on its database pages, to detect >corruptions and writes that were supposed to be atomic but failed >(because you cannot write 4K or 16K atomically on a disk drive). >