From nobody Mon May 29 23:12:24 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 4QVWX5436mz4XLD4 for ; Mon, 29 May 2023 23:12:37 +0000 (UTC) (envelope-from dpchrist@holgerdanske.com) Received: from holgerdanske.com (holgerdanske.com [184.105.128.27]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "holgerdanske.com", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4QVWX448scz3jbX for ; Mon, 29 May 2023 23:12:36 +0000 (UTC) (envelope-from dpchrist@holgerdanske.com) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=holgerdanske.com header.s=nov-20210719-112354 header.b=GtBOztE8; spf=pass (mx1.freebsd.org: domain of dpchrist@holgerdanske.com designates 184.105.128.27 as permitted sender) smtp.mailfrom=dpchrist@holgerdanske.com; dmarc=pass (policy=none) header.from=holgerdanske.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=holgerdanske.com; s=nov-20210719-112354; t=1685401953; bh=/51FVGNl2kN69gSYo0a2PooVPNA32cUB+SXelDunrI0=; h=Received:Message-ID:Date:MIME-Version:User-Agent:Subject:To: References:Content-Language:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; b=GtBOztE8AQu/ubWg8cfMZZ1+o2p69URpwHgnq2nXA9pFLdFsN1AR8Tfw8H6B4etH0 IC4BAFDTFBdUN+uTz/bcwFwiWQbgxn4UTlZOUZEQHCeDcR2gQ6YKFO32gTRGwb/HF2 mC/URTHMtDLhgY6IkodbchM5M3W7Aixysx2vjT2GK/5Pqwv5jLqu5t01iscvs7mXPG Duga/gpLIUeozq7GV5nPLBBnRZQ6zfPFERfJMi1wYcSFNnWSdWdq3rgJ1a5+ZkB4PO l9F/rRtl0Q5YlZYD0lQnpfc2fE2MFovBMP8zMpqn2est4ueGtBBMWHCk/gHU01b0rn qR8veUVRplx91bQopaVZurRYg1Cdu0PCMvVj5db1CZxEzbbprmw7lismcyl5FcLUVo YyISEuM6sx+/fGFce8KninnHQALbz0hWAvE0ji8suvxiWWN8OvFsjYheuh7ZOXyNvx RaixXhi8Kng2H1vMeJ/AX4x35poXZ8mK//bFGJPB21NsllOVsL+p3LsBuv+53pdIlb buXl8RNDT/Bldv4NIyYrJQf4L6k8GYZd3AdFAWU9TfywPyjSekCR3P/RIIrx24fhPW QHZcJIHaIB+44jKq7vxjQfo1jSE0v3PrLHiTu7vwfcp3N8mp2PWTko8rIIb0D62+Jt nG5xcdAfsIro18/+qXltw1Cs= Received: from 99.100.19.101 (99-100-19-101.lightspeed.frokca.sbcglobal.net [99.100.19.101]) by holgerdanske.com with ESMTPSA (TLS_AES_128_GCM_SHA256:TLSv1.3:Kx=any:Au=any:Enc=AESGCM(128):Mac=AEAD) (SMTP-AUTH username dpchrist@holgerdanske.com, mechanism PLAIN) for ; Mon, 29 May 2023 16:12:33 -0700 Message-ID: <00671d49-83b1-26a0-4e28-47eb0d7cb95c@holgerdanske.com> Date: Mon, 29 May 2023 16:12:24 -0700 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 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: read and write back full disk to trigger relocation To: questions@freebsd.org References: <1957739901.520492.1685310340560@ichabod.co-bxl> <0d0186c5-9542-1af3-2ce3-e28480b4b6d7@holgerdanske.com> <1961596841.3509648.1685359514813@fidget.co-bxl> Content-Language: en-US From: David Christensen In-Reply-To: <1961596841.3509648.1685359514813@fidget.co-bxl> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-4.00 / 15.00]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.999]; DMARC_POLICY_ALLOW(-0.50)[holgerdanske.com,none]; R_SPF_ALLOW(-0.20)[+a]; R_DKIM_ALLOW(-0.20)[holgerdanske.com:s=nov-20210719-112354]; MIME_GOOD(-0.10)[text/plain]; DKIM_TRACE(0.00)[holgerdanske.com:+]; ASN(0.00)[asn:6939, ipnet:184.104.0.0/15, country:US]; MLMMJ_DEST(0.00)[questions@freebsd.org]; MIME_TRACE(0.00)[0:+]; FROM_EQ_ENVFROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; PREVIOUSLY_DELIVERED(0.00)[questions@freebsd.org]; MID_RHS_MATCH_FROM(0.00)[]; ARC_NA(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_HAS_DN(0.00)[]; TO_DN_NONE(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_TLS_ALL(0.00)[] X-Rspamd-Queue-Id: 4QVWX448scz3jbX X-Spamd-Bar: --- X-ThisMailContainsUnwantedMimeParts: N On 5/29/23 04:25, Sysadmin Lists wrote: > David Christensen May 29, 2023, 12:04:41 AM >> On 5/28/23 14:45, Sysadmin Lists wrote: >>> From the dd(1) manpage: >>> >>> Do a refresh of a disk drive, in order to prevent presently recoverable >>> read errors from progressing into unrecoverable read errors: >>> >>> dd if=/dev/ada0 of=/dev/ada0 bs=1m >> >> >> gmirror(8) examples indicate the device node should be: >> >> /dev/mirror/name >> >> >> Where "name" is the argument provided when the mirror was created: >> >> # gmirror label name prov ... > > One of the examples is: > > gmirror label -v -b split -s 2048 data da0 da1 da2 > > Which tells me to look for /dev/da0, /dev/da1, /dev/da2 for the dd command. Your mail client and my mail client (Thunderbird) indent things differently. I have reformatted the above per Thunderbird conventions. I have had to do this every time I reply to your messages. I do not have this issue with most other messages I reply to. Testing dd(1) and gmirror(8): 2023-05-29 15:21:32 toor@vf1 ~ # freebsd-version ; uname -a 12.4-RELEASE-p2 FreeBSD vf1.tracy.holgerdanske.com 12.4-RELEASE-p1 FreeBSD 12.4-RELEASE-p1 GENERIC amd64 2023-05-29 15:23:05 toor@vf1 ~ # gmirror label mymirror ada3 ada4 2023-05-29 15:24:11 toor@vf1 ~ # gmirror status mymirror Name Status Components mirror/mymirror COMPLETE ada3 (ACTIVE) ada4 (ACTIVE) 2023-05-29 15:52:41 toor@vf1 ~ # dd if=/dev/ada3 of=/dev/ada3 bs=1m dd: /dev/ada3: Operation not permitted 2023-05-29 15:53:45 toor@vf1 ~ # dd if=/dev/ada4 of=/dev/ada4 bs=1m dd: /dev/ada4: Operation not permitted 2023-05-29 15:53:52 toor@vf1 ~ # dd if=/dev/mirror/mymirror of=/dev/mirror/mymirror bs=1m 1023+1 records in 1023+1 records out 1073741312 bytes transferred in 3.299006 secs (325474224 bytes/sec) This confirms that the kernel will not allow writes to mirror components when they are active, as it should. If a process could write to a component of a mirror, that would bypass the mirror driver, defeat the purpose of the mirror, allow race conditions, and result in data loss/ data corruption. David