From owner-freebsd-usb@freebsd.org Sun Dec 1 10:13:45 2019 Return-Path: Delivered-To: freebsd-usb@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 39C131C60FC for ; Sun, 1 Dec 2019 10:13:45 +0000 (UTC) (envelope-from anatoly@kazanfieldhockey.ru) Received: from kazanfieldhockey.ru (kazanfieldhockey.ru [78.138.152.250]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "kazanfieldhockey.ru", Issuer "System Administrator" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 47Qkbq6dzsz4fsX for ; Sun, 1 Dec 2019 10:13:43 +0000 (UTC) (envelope-from anatoly@kazanfieldhockey.ru) Received: from asd2 (host-175-22.static.telecet.ru [87.117.175.22] (may be forged)) (authenticated bits=0) by kazanfieldhockey.ru (8.15.2/8.15.2) with ESMTPSA id xB1A7jbP012633 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO) for ; Sun, 1 Dec 2019 13:07:47 +0300 (MSK) (envelope-from anatoly@kazanfieldhockey.ru) Date: Sun, 1 Dec 2019 13:14:16 +0300 From: Anatoly To: freebsd-usb@freebsd.org Subject: Re: pendrive clone impossible ? Message-ID: <20191201131416.3a1554ec@asd2> In-Reply-To: <20191201082801.6a8c7639@ernst.home> References: <20191130223322.1028feab.freebsd@edvax.de> <20191130234900.81464b43.freebsd@edvax.de> <20191201050341.4a02879a@asd2> <20191201082801.6a8c7639@ernst.home> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.29; amd64-portbld-freebsd10.2) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.2 (kazanfieldhockey.ru [192.168.13.2]); Sun, 01 Dec 2019 13:07:47 +0300 (MSK) X-Rspamd-Queue-Id: 47Qkbq6dzsz4fsX X-Spamd-Bar: ++++ Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of anatoly@kazanfieldhockey.ru has no SPF policy when checking 78.138.152.250) smtp.mailfrom=anatoly@kazanfieldhockey.ru X-Spamd-Result: default: False [4.84 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; IP_SCORE(0.77)[asn: 28840(3.86), country: RU(0.01)]; MIME_GOOD(-0.10)[text/plain]; MIME_TRACE(0.00)[0:+]; PREVIOUSLY_DELIVERED(0.00)[freebsd-usb@freebsd.org]; AUTH_NA(1.00)[]; RCPT_COUNT_ONE(0.00)[1]; NEURAL_SPAM_MEDIUM(0.67)[0.671,0]; TO_DN_NONE(0.00)[]; NEURAL_SPAM_LONG(0.99)[0.993,0]; DMARC_NA(0.00)[kazanfieldhockey.ru]; R_SPF_NA(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; SUBJECT_ENDS_QUESTION(1.00)[]; ASN(0.00)[asn:28840, ipnet:78.138.128.0/19, country:RU]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Dec 2019 10:13:45 -0000 On Sun, 1 Dec 2019 08:28:01 +0100 Gary Jennejohn wrote: > The geom code protects certain parts of the data area on the > drive, in particular GPT/MBR areas, unless ``sysctl > kern.geom.debugflags=16'' is run beforehand. One can see this in > many places in the geom code. > > I always set this sysctl when I know I'm going to overwrite the > first sectors of a drive. > Interesting, but I've succefully overwrited MBR many times on FreeBSD 5.x-11.x without setting this sysctl. I've learned about this sysctl when I first time failed to overwrite bsd label inside MBR slice under FreeBSD 7.1 with dd (but not MBR). There was explicit write error, not just silent succeful write to nowhere. I may be wrong, but as I remember, I newer got this trouble again starting from 10.x. Is there something new on 12.x?