From nobody Wed May 31 21:44:58 2023 X-Original-To: questions@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4QWjVF6MpBz4XgLl for ; Wed, 31 May 2023 21:45:09 +0000 (UTC) (envelope-from sysadmin.lists@mailfence.com) Received: from wilbur.contactoffice.com (wilbur.contactoffice.com [212.3.242.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4QWjV82CSFz3vHk for ; Wed, 31 May 2023 21:45:04 +0000 (UTC) (envelope-from sysadmin.lists@mailfence.com) Authentication-Results: mx1.freebsd.org; dkim=fail ("body hash did not verify") header.d=mailfence.com header.s=20210208-e7xh header.b=ktyTlSnZ; spf=pass (mx1.freebsd.org: domain of sysadmin.lists@mailfence.com designates 212.3.242.68 as permitted sender) smtp.mailfrom=sysadmin.lists@mailfence.com; dmarc=pass (policy=quarantine) header.from=mailfence.com Received: from ichabod.co-bxl (ichabod.co-bxl [10.2.0.36]) by wilbur.contactoffice.com (Postfix) with ESMTP id DCA6D939 for ; Wed, 31 May 2023 23:45:00 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1685569500; s=20210208-e7xh; d=mailfence.com; i=sysadmin.lists@mailfence.com; h=Date:From:To:Message-ID:In-Reply-To:References:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding; l=1648; bh=r6I760axyX37j3CamAYAjONggRdtybNWos50GScemGU=; b=ktyTlSnZaDXOXtojgpfeaN9Ej3wO8qsyWAhZsna80XEo9dcjHLUixzoJqIeTMVOn oQLPpgoPZDxYLCpPRMT8pcI+28claJ66GdKl+1e7Gtj6HauQCDnUx8CutTo3hAhlARL G9TIShcZ1+bDEjXDgI5KoGutWbGI+DNVH+neY9rXDLMRjH9qTgo2Faq8OXolEWkTk6W ZLgHl0Op1ovYFu8FEqhhlLp8SBnr8VluzOQZLeWkNx6dAM5iJNP3oA1L4VxAv/R3N5r y5Gz4gWv46/4ba3jux9KH6s76jlsobm7yqBqc22PeYPWXbTk/Gr0ECvApHPt3hsU5Cq Cchvbo3Iew== Date: Wed, 31 May 2023 23:44:58 +0200 (CEST) From: Sysadmin Lists To: questions@freebsd.org Message-ID: <504607037.200282.1685569498612@ichabod.co-bxl> In-Reply-To: <82a367dd-a32e-17c7-acf7-1f6992ff20af@holgerdanske.com> References: <1957739901.520492.1685310340560@ichabod.co-bxl> <0d0186c5-9542-1af3-2ce3-e28480b4b6d7@holgerdanske.com> <1961596841.3509648.1685359514813@fidget.co-bxl> <00671d49-83b1-26a0-4e28-47eb0d7cb95c@holgerdanske.com> <2025846914.656453.1685438293844@ichabod.co-bxl> <343655931.86727.1685490563032@ichabod.co-bxl> <82a367dd-a32e-17c7-acf7-1f6992ff20af@holgerdanske.com> Subject: Re: read and write back full disk to trigger relocation List-Id: User questions List-Archive: https://lists.freebsd.org/archives/freebsd-questions List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Mailer: ContactOffice Mail X-ContactOffice-Account: com:312482426 X-Spamd-Result: default: False [-2.53 / 15.00]; NEURAL_HAM_SHORT(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-0.98)[-0.983]; DMARC_POLICY_ALLOW_WITH_FAILURES(-0.50)[]; NEURAL_SPAM_LONG(0.34)[0.343]; R_SPF_ALLOW(-0.20)[+ip4:212.3.242.64/26]; MIME_GOOD(-0.10)[text/plain]; RCVD_IN_DNSWL_LOW(-0.10)[212.3.242.68:from]; XM_UA_NO_VERSION(0.01)[]; MLMMJ_DEST(0.00)[questions@freebsd.org]; RCVD_TLS_LAST(0.00)[]; ASN(0.00)[asn:10753, ipnet:212.3.242.64/26, country:US]; MIME_TRACE(0.00)[0:+]; FROM_EQ_ENVFROM(0.00)[]; BLOCKLISTDE_FAIL(0.00)[212.3.242.68:query timed out]; DKIM_TRACE(0.00)[mailfence.com:-]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; DMARC_POLICY_ALLOW(0.00)[mailfence.com,quarantine]; PREVIOUSLY_DELIVERED(0.00)[questions@freebsd.org]; RCPT_COUNT_ONE(0.00)[1]; TO_DN_NONE(0.00)[]; R_DKIM_REJECT(0.00)[mailfence.com:s=20210208-e7xh]; ARC_NA(0.00)[] X-Rspamd-Queue-Id: 4QWjV82CSFz3vHk X-Spamd-Bar: -- X-ThisMailContainsUnwantedMimeParts: N > ---------------------------------------- > From: David Christensen > Date: May 31, 2023, 12:30:43 AM > To: > Subject: Re: read and write back full disk to trigger relocation > > > On 5/30/23 16:49, Sysadmin Lists wrote: > > David Christensen May 30, 2023, 4:16:09 PM > >> I would say the experiment should be repeated on real HDD's, but how do > >> I detect if identical data has being written to the platters? The HDD > >> controller also has a cache and could optimize away such writes. > > > > Isn't that what dd is claiming authoritatively to be doing? Otherwise, putting > > that example in the manpage is dangerous and can lead to unexpected data loss. > > > > I don't speak C++ very good, but here's the source: > > https://github.com/coreutils/coreutils/blob/master/src/dd.c > > > > > Looking at FreeBSD code will not provide information about the HDD > controller hardware and firmware. > > > David > > You're still not getting it: *they* are the ones claiming to be effectively writing out those blocks. It's up to them to validate that claim by accounting for whatever HDD controller hardware and firmware are doing. There's no magic at play; either the source code proves their claims and assumptions or it doesn't. Perhaps you can submit a bug report asking them to remove that example from the manpage, with something like "you can't make that claim without knowing what every HDD controller hardware and firmware are doing." Will be interested in their response. -- Sent with https://mailfence.com Secure and private email