From owner-freebsd-fs@freebsd.org Tue Aug 4 15:54:54 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 49196378907 for ; Tue, 4 Aug 2020 15:54:54 +0000 (UTC) (envelope-from matthew.ahrens@delphix.com) Received: from mail-ed1-x532.google.com (mail-ed1-x532.google.com [IPv6:2a00:1450:4864:20::532]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4BLfTT3zmlz4XBD for ; Tue, 4 Aug 2020 15:54:53 +0000 (UTC) (envelope-from matthew.ahrens@delphix.com) Received: by mail-ed1-x532.google.com with SMTP id c10so546268edk.6 for ; Tue, 04 Aug 2020 08:54:53 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=+WKfzwdEuQVYvogm5R/DGKpS4AN6sUFuQ4F9BftYFB0=; b=ouFAclIFo40etlwWSsH8LMZGrnCS+cvpLeqI5nKHifA3eIMt+J7H96721o2SKlvf9l 8nVPsevDxZuSt57CRcyC515iouAhXqnyNzlQ9C56SexCNsHt5J1lh1V/UAi6EImR/PFb pvP1JsiUWx1UehzktUkmF7jKK4JEZKD4/dFDK19cIHfnFwKevNjU7buJqQ/kduEb4x1d 9xf9bLgSiMQiCsOf2XW+wxUwLsxZ4JIimj+PcEK88ulqY7ZbWbfDwbXrVMsD+faAvjkB i90gqQNqgDw8W/dbQso4mPsE1Yfk/NKFOcd31VmM47v622oh8ZZ0SOYiEXLSX46GfV3D 1PMg== X-Gm-Message-State: AOAM532jZtpJ7wXAj1R3CgaAUD0jCzINcRDQGgF02umIrXrGE/0pf+Cw xO9/zt/dk86Uu6XI9SjH01mqs3wTgAZ450qeBoAPsQ== X-Google-Smtp-Source: ABdhPJzlnTS/lGZ0fGYmYn7GJvS4ywSg7gjftMmezBdaBmx0GdKHXYshLYR2IHJPkAzh/OR0HyUsoeREKuECWc20nNQ= X-Received: by 2002:a05:6402:1282:: with SMTP id w2mr20340189edv.183.1596556491751; Tue, 04 Aug 2020 08:54:51 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Matthew Ahrens Date: Tue, 4 Aug 2020 08:54:41 -0700 Message-ID: Subject: Re: zfs scrub enable by default To: Steve Wills Cc: freebsd-fs , George Wilson X-Rspamd-Queue-Id: 4BLfTT3zmlz4XBD X-Spamd-Bar: --- X-Spamd-Result: default: False [-3.02 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.01)[-1.011]; R_DKIM_ALLOW(-0.20)[delphix.com:s=google]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36]; NEURAL_HAM_LONG(-1.01)[-1.010]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-fs@freebsd.org]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[delphix.com:+]; DMARC_POLICY_ALLOW(-0.50)[delphix.com,quarantine]; RCVD_IN_DNSWL_NONE(0.00)[2a00:1450:4864:20::532:from]; NEURAL_HAM_SHORT(-0.29)[-0.295]; FORGED_SENDER(0.30)[matt@delphix.com,matthew.ahrens@delphix.com]; MIME_TRACE(0.00)[0:+,1:+,2:~]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; FROM_NEQ_ENVFROM(0.00)[matt@delphix.com,matthew.ahrens@delphix.com]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.33 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: Tue, 04 Aug 2020 15:54:54 -0000 This question was raised elsewhere, and I agree with this reply from George Wilson, my colleague and an expert in the i/o subsystems of ZFS as well as having lots of experience with customers: Having scrubs enabled by default is a great idea but at Sun (and Delphix > too) we found that the impact was often too much for some > workloads/customers. This is the challenge we faced and why there was never > a policy to enable it everywhere. We did explore ideas to make the impact > less and to be able to always scrub. Some of those ideas included periodic > or continuous scrubs where the impact could be reduced by only scrubbing > portions of the pool at a time, at a reduced i/o rate. At Delphix, we have > investigated similar concepts and one of our interns prototyped one of the > ideas.Much has changed since the early scrub days and revisiting some of > the earlier ideas and investigating new ones is probably a good topic for > the community. I do think that just enabling scrub by default without > further enhancements would still be too impactful for some customers but > the concept definitely has merit. --matt On Mon, Aug 3, 2020 at 9:10 AM 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" >