From owner-cvs-all@FreeBSD.ORG Mon Dec 17 14:55:33 2007 Return-Path: Delivered-To: cvs-all@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C377616A41B; Mon, 17 Dec 2007 14:55:33 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222]) by mx1.freebsd.org (Postfix) with ESMTP id 89FA613C474; Mon, 17 Dec 2007 14:55:33 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (unknown [192.168.61.3]) by phk.freebsd.dk (Postfix) with ESMTP id 0F60017105; Mon, 17 Dec 2007 14:55:32 +0000 (UTC) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.14.2/8.14.2) with ESMTP id lBHEtVsD011420; Mon, 17 Dec 2007 14:55:31 GMT (envelope-from phk@critter.freebsd.dk) To: "Bruce M. Simpson" From: "Poul-Henning Kamp" In-Reply-To: Your message of "Mon, 17 Dec 2007 14:43:55 GMT." <47668B2B.5030206@incunabulum.net> Date: Mon, 17 Dec 2007 14:55:31 +0000 Message-ID: <11419.1197903331@critter.freebsd.dk> Sender: phk@critter.freebsd.dk Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, "Bruce M. Simpson" , cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sbin/atacontrol atacontrol.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 Dec 2007 14:55:33 -0000 In message <47668B2B.5030206@incunabulum.net>, "Bruce M. Simpson" writes: >Poul-Henning Kamp wrote: >> I have the attached patch in sos@ mailbox for approval, that adds >> BIO_DELETE support for the ata driver. >> >> I also want to implement a -E option to fsck(8) to erase all >> unallocated blocks. >> >> And finally the big item: msdosfs and ufs support to issue BIO_DELETE >> when files are deleted. UFS is nasty because of soft-updates. >> > >Aha, I understand now. CFA and SATA vendors have gone off in two >separate directions: > * PATA and SATA drives, for a few years now, have tended to rewrite one >cylinder at a time, which implies erasing the data on that cylinder. Everybody denies this in the stongest possibly way whenever I ask them, so far I have not seen this claim substantiated by any fact or person who would be in a position to know. > * NAND Flash devices should not have their sectors erased unless >absolutely necessary, to implement wear levelling. Wrong, almost exactly the opposite in fact: Flash devices using wear-levelling should have data erased as soon as possible to give the wear-levelling the maximum amount of information and available space to work with. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.