From owner-freebsd-stable@freebsd.org Wed May 8 06:48:26 2019 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 31C7D159FD57 for ; Wed, 8 May 2019 06:48:26 +0000 (UTC) (envelope-from borjam@sarenet.es) Received: from cu01176b.smtpx.saremail.com (cu01176b.smtpx.saremail.com [195.16.151.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id E6C148EA13 for ; Wed, 8 May 2019 06:48:24 +0000 (UTC) (envelope-from borjam@sarenet.es) Received: from [172.16.8.250] (unknown [192.148.167.11]) by proxypop01.sare.net (Postfix) with ESMTPA id DE4369DFA67; Wed, 8 May 2019 08:48:15 +0200 (CEST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.8\)) Subject: Re: ZFS... From: Borja Marcos In-Reply-To: Date: Wed, 8 May 2019 08:48:14 +0200 Cc: freebsd-stable@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <30506b3d-64fb-b327-94ae-d9da522f3a48@sorbs.net> <56833732-2945-4BD3-95A6-7AF55AB87674@sorbs.net> <3d0f6436-f3d7-6fee-ed81-a24d44223f2f@netfence.it> <17B373DA-4AFC-4D25-B776-0D0DED98B320@sorbs.net> <70fac2fe3f23f85dd442d93ffea368e1@ultra-secure.de> <70C87D93-D1F9-458E-9723-19F9777E6F12@sorbs.net> <5ED8BADE-7B2C-4B73-93BC-70739911C5E3@sorbs.net> <2e4941bf-999a-7f16-f4fe-1a520f2187c0@sorbs.net> <20190430102024.E84286@mulder.mintsol.com> <41FA461B-40AE-4D34-B280-214B5C5868B5@punkt.de> <20190506080804.Y87441@mulder.mintsol.com> <08E46EBF-154F-4670-B411-482DCE6F395D@sorbs.net> <33D7EFC4-5C15-4FE0-970B-E6034EF80BEF@gromit.dlib.vt.edu> To: Walter Parker X-Mailer: Apple Mail (2.3445.104.8) X-Rspamd-Queue-Id: E6C148EA13 X-Spamd-Bar: ----- X-Spamd-Result: default: False [-5.23 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip4:195.16.151.0/24]; MV_CASE(0.50)[]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_LAST(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; NEURAL_HAM_SHORT(-0.81)[-0.810,0]; TO_MATCH_ENVRCPT_SOME(0.00)[]; MX_GOOD(-0.01)[smtp.sarenet.es,smtp.sarenet.es,smtp.sarenet.es]; RCPT_COUNT_TWO(0.00)[2]; RCVD_IN_DNSWL_NONE(0.00)[151.151.16.195.list.dnswl.org : 127.0.10.0]; SUBJ_ALL_CAPS(0.45)[6]; DMARC_POLICY_ALLOW(-0.50)[sarenet.es,reject]; IP_SCORE(-2.56)[ip: (-7.13), ipnet: 195.16.128.0/19(-3.29), asn: 3262(-2.43), country: ES(0.04)]; FREEMAIL_TO(0.00)[gmail.com]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:3262, ipnet:195.16.128.0/19, country:ES]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 08 May 2019 06:48:26 -0000 > On 8 May 2019, at 05:09, Walter Parker wrote: > Would a disk rescue program for ZFS be a good idea? Sure. Should the = lack > of a disk recovery program stop you from using ZFS? No. If you think = so, I > suggest that you have your data integrity priorities in the wrong = order > (focusing on small, rare events rather than the common base case). ZFS is certainly different from other flesystems. Its self healing = capabilities help it survive problems=20 that would destroy others. But if you reach a level of damage past that = =E2=80=9Ctolerable=E2=80=9D threshold consider yourself dead. Is it possible at all to write an effective repair tool? It would be = really complicated. By the way, ddrescue can help in a multiple drive failure scenery with = ZFS. If some of the drives are showing the typical problem of =E2=80=9Cflaky=E2=80=9D sectors with a = lot of retries slowing down the whole pool you can shut down the system or at least export the pool, copy the required = drive/s to fresh ones, replace the flaky drives and try to import the pool. I would first do the experiment = to make sure it=E2=80=99s harmless, but ZFS relies on labels written on the disks to import a pool = regardless of disk controller topology, devices names, uuids, or whatever. So a full disk copy should work.=20 Michelle, were you doing periodic scrubs? I=E2=80=99m not sure you = mentioned it.=20 Borja.