Date: Mon, 3 Aug 2020 17:12:09 -0400 From: Charles Sprickman <spork@bway.net> To: Allan Jude <allanjude@freebsd.org> Cc: freebsd-fs@freebsd.org Subject: Re: zfs scrub enable by default Message-ID: <0E22A84A-DAAF-4651-865B-0AE038C7C3F4@bway.net> In-Reply-To: <24edb075-155c-439d-1ef5-541893036429@freebsd.org> References: <cca34d1a-1892-41ec-ce45-84865100c6e1@FreeBSD.org> <24edb075-155c-439d-1ef5-541893036429@freebsd.org>
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[-- Attachment #1 --] > On Aug 3, 2020, at 4:25 PM, Allan Jude <allanjude@freebsd.org> wrote: > > On 2020-08-03 12:10, Steve Wills wrote: >> Hi, >> >> I wonder why we don't enable zfs periodic scrub by default? >> >> https://svnweb.freebsd.org/base/head/usr.sbin/periodic/periodic.conf?view=markup#l162 >> >> >> Anyone happen to know? >> >> Thanks, >> Steve >> >> _______________________________________________ >> freebsd-fs@freebsd.org mailing list >> https://lists.freebsd.org/mailman/listinfo/freebsd-fs >> To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" > > I think switching this to on-by-default is a good thing. > > To be clear, which the check is part of 'periodic daily', it only > triggers a scrub if it has been more than 35 days since the last scrub. > > FreeNAS already has does this, and that accounts for a large number of > FreeBSD ZFS deployments. > > There is tuning you can do in ZFS to try to lessen the impact of a scrub > on your production workloads. > > > The periodic script lets you select which pools to include (defaults to > all), so you can tune it to only scrub your root pool every 35 days, and > not the large pool that might take too long to scrub or whatever. It > also lets you set a different threshold for each pool. > > So I don't see any reason not to enable it by default, and just document > how to adjust it if people really need to disable it. Honestly, I think > those who are disabling it are doing themselves a disservice. I 100% agree. I think often FreeBSD defaults tend to favor the experienced user and throw the newbies under the bus. In this case there were arguments against that amounted to “What about people running large production systems”, to which my answer would be, “What about them? They are experienced, read all the mailing lists, would know right away what was happening when they saw a scrub running, and already know how to disable it and could make the case for disabling or swapping in their own solution”. Contrast with the random home user, noob, casual user who would likely benefit from whatever data protection, pre-emptive failure notification, etc. this would provide (for example I’ve had a scrub show me a failing drive before SMART did). Charles > > -- > Allan Jude > [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQEzBAEBCAAdFiEECbwhUg0jlYPK5QaKiZUhnP6GpPYFAl8ofakACgkQiZUhnP6G pPbhfwgAsVMetrmx5pgpt4V0oRElZffcMtUdvSYh5gWEW6vESu+rBdScR2tqEXwG pjlmhg9rZBnRdHKWe4NZQ3S7GHTSnr4jK60tkpoVzy4zdPNiFOkl1MKOsyZzQPfC 6fGT1bfEfcMPKA5QrwGU6hJ4PoB7XnLPeFwZ91Ilp+tnj9odfSo0tbAAjHCWe+rR mgN1Ey5MGOnhNw3ey+cn6YKqffGYsns32dwTaLnV77yRFkQS1Tj+DMnkpFfTQf43 CocG1ooPnr7+1LrtR26qzy8yWF1fyxxwDbP/MGXsfvIv/cHKJuD30KxXT1Q2qDND xOno5tnFtlNLBLIs9EakWFXv0uHTfQ== =yjDH -----END PGP SIGNATURE-----
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