From nobody Thu Feb 20 23:50:30 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 4YzVRF1Nlqz5pbws for ; Thu, 20 Feb 2025 23:51:53 +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 4YzVRB2YdYz44mt for ; Thu, 20 Feb 2025 23:51:49 +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=TF+AoNUJ; dmarc=none; 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 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 51KNoTpH000800 for ; Fri, 21 Feb 2025 10:50:30 +1100 (AEDT) (envelope-from dewayne@heuristicsystems.com.au) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=heuristicsystems.com.au; s=hsa; t=1740095430; x=1740700231; bh=MsXJ9BvTz6f24n1V2VJTfkvPHh+hUWJ295BCdjOZ/KI=; h=Message-ID:Date:To:From:Subject; b=TF+AoNUJQEV6wQmBxG2BopSMYYogR9BsirHCM/W2kMAjqdlAlHxLeHcvdIvOnmqLu 7oStvruoZyjZ3jjENfbr1RzMhMfQfePH3gwBEfqfqd3qlWzJTP51UkdlbVlXm068HW hqgP//mYjgRnp34kT8ruoB67v7QdzWRjmwp1KsD9ckQmczFPNI1P9 X-Authentication-Warning: b3.hs: Host bigears.hs [10.0.5.4] claimed to be [10.0.5.4] Message-ID: Date: Fri, 21 Feb 2025 10:50:30 +1100 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 Content-Language: en-GB To: questions@freebsd.org From: Dewayne Geraghty Subject: GPT secondary corrupt. Is dd'ing the first 40 sectors as a backup sufficient? Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-5.00 / 15.00]; DWL_DNSWL_MED(-2.00)[heuristicsystems.com.au:dkim]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_LONG(-1.00)[-1.000]; SUBJECT_ENDS_QUESTION(1.00)[]; NEURAL_HAM_SHORT(-1.00)[-0.999]; RCVD_DKIM_ARC_DNSWL_MED(-0.50)[]; ONCE_RECEIVED(0.20)[]; R_DKIM_ALLOW(-0.20)[heuristicsystems.com.au:s=hsa]; R_SPF_ALLOW(-0.20)[+mx]; RCVD_IN_DNSWL_MED(-0.20)[203.41.22.115:from]; MIME_GOOD(-0.10)[text/plain]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_TRACE(0.00)[heuristicsystems.com.au:+]; RCVD_TLS_LAST(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; MIME_TRACE(0.00)[0:+]; DMARC_NA(0.00)[heuristicsystems.com.au]; ASN(0.00)[asn:1221, ipnet:203.40.0.0/13, country:AU]; ARC_NA(0.00)[]; TO_DN_NONE(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_COUNT_ONE(0.00)[1]; PREVIOUSLY_DELIVERED(0.00)[questions@freebsd.org]; MID_RHS_MATCH_FROM(0.00)[]; MLMMJ_DEST(0.00)[questions@freebsd.org]; RCVD_VIA_SMTP_AUTH(0.00)[]; HAS_XAW(0.00)[] X-Rspamd-Queue-Id: 4YzVRB2YdYz44mt X-Spamd-Bar: ---- I have a full disk gmirror on 12.4 using the MBR scheme. As I'm migrating to 14.2S and would like to use GPT scheme, so to my questions: 1. Is there a sysctl, or flag (somewhere) to disable " the secondary GPT table is corrupt or invalid." notifications? And the fear-inspiring # gpart show md0 => 40 32688 md0 GPT (16M) [CORRUPT] 2. To recover a damaged primary partition, is it sufficient to restore from a dd of the first 40 sectors of the disk, taken after disk setup (formatting and labelling the disk)? 3. Is the partition header written to without my involvement? (eg is the clean bit set/stored in the primary or a "sub-"partition (p*)?) I'm sorry if my language is a bit clumsy I'm used to slices and partition. Cheers, Dewayne PS Sadly ZFS doesn't support labels (re MAC_[MLS,BIBA])