From owner-freebsd-geom@freebsd.org Mon Dec 9 15:51:28 2019 Return-Path: Delivered-To: freebsd-geom@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 31C111D9A23 for ; Mon, 9 Dec 2019 15:51:28 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.nyi.freebsd.org (unknown [127.0.1.3]) by mx1.freebsd.org (Postfix) with ESMTP id 47Wnjr0flHz3HJd for ; Mon, 9 Dec 2019 15:51:28 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id 14B8E1D9A22; Mon, 9 Dec 2019 15:51:28 +0000 (UTC) Delivered-To: geom@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 147A81D9A21 for ; Mon, 9 Dec 2019 15:51:28 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 47Wnjq6sNHz3HJc for ; Mon, 9 Dec 2019 15:51:27 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id E6DDC1CD6C for ; Mon, 9 Dec 2019 15:51:27 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id xB9FpRjq057264 for ; Mon, 9 Dec 2019 15:51:27 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id xB9FpR0m057263 for geom@FreeBSD.org; Mon, 9 Dec 2019 15:51:27 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: geom@FreeBSD.org Subject: [Bug 242341] GEOM / GEOM_PART: silent discard MBR modification Date: Mon, 09 Dec 2019 15:51:28 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 12.1-RELEASE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: ae@FreeBSD.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: geom@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Dec 2019 15:51:28 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D242341 --- Comment #7 from Andrey V. Elsukov --- (In reply to Tomasz "CeDeROM" CEDRO from comment #6) And again, You didn't provided any useful info. > 1. dd if=3D/dev/da0 of=3D/dev/da1 bs=3D512 count=3D1 does not copy anythi= ng. Please, use script(1) command if you unable to make a copy from your termin= al. Should be something like this: # dd if=3D/dev/da0 of=3D/dev/da1 count=3D1 1+0 records in 1+0 records out 512 bytes transferred in 0.001958 secs (261495 bytes/sec) You can use hexdump(1) command to check the result of your copy, e.g. # dd if=3D/dev/da1 count=3D1 | hexdump -vC > 2. dd if=3D/dev/zero of=3D/dev/da1 bs=3D512 count=3D1 zeroes the mbr. This looks impossible, if first command doesn't work, this also wont work. > Can you please explain in detail what does it mean exactly "ignores the=20 > partition table"? I guess here is the problem. There is no problem, all described in gpart(8) man page. "Ignores" means th= at GEOM_PART class will not create geom object of type MBR and there will no partitions appears.=20 > If the "partition table is ignored", then why it is silently ignored,=20 > writes to MBR goes to /dev/null, reads from MBR does not update disk > layout, while it is possible to write to the rest of the disk? > Why the whole disk is not locked against writing in a clearly=20 > distinguishable manner? Like error return code from DD and error=20 > messages in DMESG? I don't think that something like this happens in reality :) > So you confirm that the write to MBR was silently discared and the whole > situation is indeed managed by GEOM_PART. This is exactly the problem I=20 > am reporting. Thank you :-) You still misunderstand how all things work. There are different GEOM objec= ts, and when MBR is ignored, GEOM_PART discards nothing, since there is no rela= ted GEOM object. This is why I asked to show the output of `gpart show` and `gp= art list` commands. --=20 You are receiving this mail because: You are the assignee for the bug.=