From nobody Thu Jun 26 05:39:36 2025 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 4bSSJ04b08z60591 for ; Thu, 26 Jun 2025 05:42:24 +0000 (UTC) (envelope-from dewayne@heuristicsystems.com.au) Received: from heuristicsystems.com.au (hermes.heuristicsystems.com.au [203.41.22.115]) (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-signature RSA-PSS (2560 bits) client-digest SHA256) (Client CN "hermes.heuristicsystems.com.au", Issuer "Heuristic Systems Type 4 Host CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4bSSHw6tW3z4B1L for ; Thu, 26 Jun 2025 05:42:20 +0000 (UTC) (envelope-from dewayne@heuristicsystems.com.au) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=heuristicsystems.com.au header.s=hsa header.b=VVPiRu5D; spf=pass (mx1.freebsd.org: domain of dewayne@heuristicsystems.com.au designates 203.41.22.115 as permitted sender) smtp.mailfrom=dewayne@heuristicsystems.com.au; dmarc=none Received: from [10.0.5.4] (bigears.hs [10.0.5.4]) (authenticated bits=0) by heuristicsystems.com.au (8.15.2/8.15.2) with ESMTPA id 55Q5dbQp017565 for ; Thu, 26 Jun 2025 15:39:37 +1000 (AEST) (envelope-from dewayne@heuristicsystems.com.au) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=heuristicsystems.com.au; s=hsa; t=1750916377; x=1751521178; bh=juh+6/eiYOEJcFTviWdijbrFJjAeKUeWHtgdk0ftD6E=; h=Message-ID:Date:Subject:To:From; b=VVPiRu5Di8ikdANXf0fG7llJ8hcJrjqq1evFfYsxxlk/je+tvPmDgF6wFZyydNBBa TCJ42+MuSVrAS5oq7RwSC6+1ildVmzMb2c2lcj0q20ZgY7itS7r3VbxbqYRTxc9KM6 HCuYbrmkmuf9HfXnf/Vx9/2PAv4qhc3PEKauZB83KNRC9917/INnN X-Authentication-Warning: b3.hs: Host bigears.hs [10.0.5.4] claimed to be [10.0.5.4] Message-ID: Date: Thu, 26 Jun 2025 15:39:36 +1000 List-Id: User questions List-Archive: https://lists.freebsd.org/archives/freebsd-questions List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: freebsd-questions@freebsd.org Sender: owner-freebsd-questions@FreeBSD.org MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Wiping a disk partition To: questions@freebsd.org References: Content-Language: en-GB From: Dewayne Geraghty In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-2.21 / 15.00]; DWL_DNSWL_MED(-2.00)[heuristicsystems.com.au:dkim]; NEURAL_HAM_SHORT(-0.99)[-0.989]; NEURAL_SPAM_MEDIUM(0.92)[0.922]; NEURAL_SPAM_LONG(0.85)[0.853]; RCVD_DKIM_ARC_DNSWL_MED(-0.50)[]; R_DKIM_ALLOW(-0.20)[heuristicsystems.com.au:s=hsa]; RCVD_IN_DNSWL_MED(-0.20)[203.41.22.115:from]; ONCE_RECEIVED(0.20)[]; R_SPF_ALLOW(-0.20)[+mx]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; DMARC_NA(0.00)[heuristicsystems.com.au]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_ONE(0.00)[1]; FROM_HAS_DN(0.00)[]; TO_DN_NONE(0.00)[]; RCVD_TLS_LAST(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_ONE(0.00)[1]; ASN(0.00)[asn:1221, ipnet:203.40.0.0/13, country:AU]; MID_RHS_MATCH_FROM(0.00)[]; MLMMJ_DEST(0.00)[questions@freebsd.org]; PREVIOUSLY_DELIVERED(0.00)[questions@freebsd.org]; DKIM_TRACE(0.00)[heuristicsystems.com.au:+]; HAS_XAW(0.00)[] X-Rspamd-Queue-Id: 4bSSHw6tW3z4B1L X-Spamd-Bar: -- Hi Washington, MAGNETIC Media I wasn't familiar with David's approach so I visited the "Australian Defence Signals Directorate's" ISM Manual "The Advanced Technology Attachment (ATA) secure erase command was built into the firmware of post-2001 non-volatile magnetic hard drives and is able to access sectors that have been added to the growth defects table. (ie bad sectors)" which is good news. Thanks David for the explanation. FLASH Media Also the ISM states for: "For non-volatile flash memory media, a technique known as wear levelling ensures that writes are distributed evenly across each memory block. This feature necessitates non-volatile flash memory media being overwritten with a random pattern twice as this helps to ensure that all memory blocks are overwritten". So dd is a good solution as mentioned by others. There's a plethora of standard and methods (NIST SP 800-88 Guidelines for Media Sanitization, p32-35 is useful), but this is sufficient. PS I reference the ASD ISM because its widely required in my location (Australia) and follows NIST800-53r pretty well.