From owner-freebsd-fs@freebsd.org Wed Aug 5 17:57:37 2020 Return-Path: Delivered-To: freebsd-fs@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 4D68737E744 for ; Wed, 5 Aug 2020 17:57:37 +0000 (UTC) (envelope-from allanjude@freebsd.org) Received: from tor1-11.mx.scaleengine.net (tor1-11.mx.scaleengine.net [IPv6:2001:470:1:474::25]) (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 did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4BMK8c49tjz3ygB for ; Wed, 5 Aug 2020 17:57:36 +0000 (UTC) (envelope-from allanjude@freebsd.org) Received: from [10.1.1.2] (Seawolf.HML3.ScaleEngine.net [209.51.186.28]) (Authenticated sender: allanjude.freebsd@scaleengine.com) by tor1-11.mx.scaleengine.net (Postfix) with ESMTPSA id 2753D21336 for ; Wed, 5 Aug 2020 17:57:30 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.10.3 tor1-11.mx.scaleengine.net 2753D21336 Subject: Re: zfs scrub enable by default To: freebsd-fs@freebsd.org References: <105090343.294898.1596586694925.JavaMail.zimbra@gray.id.au> From: Allan Jude Autocrypt: addr=allanjude@freebsd.org; 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WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="aT8JEaXoPWqjghaFErxWVY9e6WSfUFRS8" X-Rspamd-Queue-Id: 4BMK8c49tjz3ygB X-Spamd-Bar: / Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [0.00 / 15.00]; local_wl_from(0.00)[freebsd.org]; ASN(0.00)[asn:6939, ipnet:2001:470::/32, country:US] X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Aug 2020 17:57:37 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --aT8JEaXoPWqjghaFErxWVY9e6WSfUFRS8 Content-Type: multipart/mixed; boundary="6pL0dlkpiRaE5F36b7jNbDtc2C74GyX9B"; protected-headers="v1" From: Allan Jude To: freebsd-fs@freebsd.org Message-ID: <52faf0aa-2c91-97c0-e0b9-ce8c1b513cbd@freebsd.org> Subject: Re: zfs scrub enable by default References: <105090343.294898.1596586694925.JavaMail.zimbra@gray.id.au> In-Reply-To: --6pL0dlkpiRaE5F36b7jNbDtc2C74GyX9B Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020-08-05 00:32, Ryan Moeller wrote: > On Tue, Aug 4, 2020 at 11:36 PM PK1048.COM wrote: >> >> On Aug 4, 2020, at 8:18 PM, Grant Gray via freebsd-fs wrote: >> >>> 2. That scrubbing PREVENTS data loss. Scrubbing can only tell you abo= ut data loss AFTER it happens. Yes, it could alert you to a problem that = prevents further data loss, but it's already too late. Scrubbing is not a= substitute for RAID, backups and proactive SMART testing. >> >> Scrubbing does not directly prevent data loss. Scrubbing identifies da= ta returned from the underlying device as corrupt or incorrect. If the zp= ool has sufficient redundancy, then no data is lost. >> >> But, normal ZFS operation also identifies incorrect date returned from= the underlying device(s). >> >> While I have only managed a few hundred drives under ZFS, I cannot rec= all one case where a proactive scrub found bad data _before_ normal opera= tions. Once a checksum error is reported via `zpool status` then I have f= ound a scrub useful to determine the extent of the drive failure. >> >> I know there are others with thousands of drives managed under ZFS and= their experience may differ. >> >=20 >> In terms of whether the periodic scrub should be enabled by default, I= am undecided, as I can see both sides of the argument. I would prefer to= make it a user choice during installation as one of the ZFS options (suc= h as native 4K drives, ashift=3D12 or mirrored swap). Make the default en= abled, but by putting it in the installation options, those who know they= need it disabled can make sure it is off from day one and not have a rud= e surprise the first time it runs (35 days after installation). >> >=20 > I don't think it was mentioned on this list, but that seems to be the > current direction this is heading. Providing an option in the > installer, whether enabled by default or not, should address > everyone's concerns. >=20 I don't think the installer is the place to define defaults though. So I'd lean towards: on by default, but offer it as an option in the installer, so they can choose to disable it. --=20 Allan Jude --6pL0dlkpiRaE5F36b7jNbDtc2C74GyX9B-- --aT8JEaXoPWqjghaFErxWVY9e6WSfUFRS8 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (MingW32) iQIcBAEBAgAGBQJfKvMJAAoJEBmVNT4SmAt+oPYP/j1xwimOgSWxNJyh3exXqnqs VTUOefDcfH8EJkpJ60SB01Rki51LATvBl3+4ZNwmjMGBCooi3IcsLPDyhcbQXUE0 B+PXOQj4tGWu5FiQ6MEAvO9MQit3/yLyYeeKMdf1heABlo4KE0APg/MbgPbXDmwU lJk1GHnFEBEMwI2j55sO034xs3AYNFsg2G0rA0UfIr6nsEnCGDACul8reUhqlJDk YSu23Sw7q1ubmy1tlcNm1dguQplBtecH0cvB6KHWEup6zEgvEJghRKxJaky5lQNR bSvI00fK28uEJiiw89XtwTz5bUGQ6uk5TEZXNODPjR7u2GWElZDXzqb0+W8L4vHW aKM5T6pq4og7EUmmF7IN1y4La3ciLURoRt8exqsr2leodFLGPTbUEHd9x8DfgD9e Fjd+YrVaCFIlQaW4i+C8FGoLrm5uXFuB1pePGTFFA8BwpzE5abHAedJxk4CtwHzS PCwwJuAWJpTdXKcYsXEWNRbMh/ScpGcD/udmiRCQ5ru1DD6uhPy88eOy46sZ24Rc HgRBkxlWpAR16z1Hoj07DLLR7FzQRdnvlfImVlC9OnlCjas0dOH4Nlumw5H0/NnQ aw489TQiWAVkrR7zo8PAfHlWdgumzxHX4dgQkJiDnLSeXFZuj79eE+1pwBNb/fEk fjXeVep/R1l/35FsnkOZ =zg85 -----END PGP SIGNATURE----- --aT8JEaXoPWqjghaFErxWVY9e6WSfUFRS8--