From mboxrd@z Thu Jan 1 00:00:00 1970 From: Toby Thain Subject: Re: Checksumming blocks? [was Re: the " 'official' point of view" expressed by kernelnewbies.org regarding reiser4 inclusion] Date: Fri, 4 Aug 2006 11:56:24 +0400 Message-ID: <8618C0ED-A530-4414-8B86-3D6B42C84604@smartgames.ca> 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 (Apple Message framework v752.2) Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <44D285DF.7060905@elegant-software.com> List-Id: Content-Type: text/plain; charset="us-ascii"; delsp="yes"; format="flowed" To: Russell Leighton Cc: ReiserFS List On 4-Aug-06, at 3:25 AM, Russell Leighton wrote: > > 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)? ZFS will correct from a good mirror (http://blogs.sun.com/roller/page/ bonwick?entry=zfs_end_to_end_data). --T > > 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). >> >