From owner-freebsd-fs@freebsd.org Wed Aug 5 15:24:55 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 6AECB3796E9 for ; Wed, 5 Aug 2020 15:24:55 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mail-ot1-f42.google.com (mail-ot1-f42.google.com [209.85.210.42]) (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 4BMFmP3bbkz3Tq9 for ; Wed, 5 Aug 2020 15:24:53 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mail-ot1-f42.google.com with SMTP id e11so9427012otk.4 for ; Wed, 05 Aug 2020 08:24:53 -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=LsNlRDigcehWOqkeXXU4nY+Ib7F7NMRcU7FlgYymE40=; b=s331bI2jmmcZfnavzKARASKej7BEibz5ss9aKkppSm5qa3AZdykAreyMEyGb0PT9i1 1Vg9GfyHKRTUcmA8o1DpaJhmZKjfnu6aWoRemT2oKG4Uravp/KI6Dc35c46PBOpyR5+l DBzthtFB8c4USfY90LQd34Y3BEr46U1KokKX58xQD4wR/DL8IIhKEeMyWs27toZL3GFy 5E6FKeFAM7DvrDBTdmfh3z45q4uFVu9K0qJxdI4RK8RxgZD8xSjBeNgdc1aPoQcUvlMR Kh4vMTatQSUKt8p2VyZHavz0E+JkWWY0KX5Sn6NW3JgWgSYGdWOVOvxJTjsIKJ06rmiu pEKg== X-Gm-Message-State: AOAM530ELz29yAtJXptd2n/BfxdLG8UM+hi06vAki6/X5MmzNEmI4NcW 7VvRRR0Ra/E7Um1jAtXrOfWYXrOMjZUcdU1JkZI= X-Google-Smtp-Source: ABdhPJxBAYD7yIGtBalWpXcwlnPtOvCMmR9C0/6WxQpopT3O8JnwFWGTeDsJFnEf4WImTAOyPW07ri9PTjsfqQwxALQ= X-Received: by 2002:a9d:4b82:: with SMTP id k2mr3249262otf.18.1596641092143; Wed, 05 Aug 2020 08:24:52 -0700 (PDT) MIME-Version: 1.0 References: <105090343.294898.1596586694925.JavaMail.zimbra@gray.id.au> <1327e123-35df-1e27-af7a-7225dae91a21@inbox.lv> In-Reply-To: <1327e123-35df-1e27-af7a-7225dae91a21@inbox.lv> From: Alan Somers Date: Wed, 5 Aug 2020 09:24:40 -0600 Message-ID: Subject: Re: zfs scrub enable by default To: John Long Cc: freebsd-fs X-Rspamd-Queue-Id: 4BMFmP3bbkz3Tq9 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of asomers@gmail.com designates 209.85.210.42 as permitted sender) smtp.mailfrom=asomers@gmail.com X-Spamd-Result: default: False [-2.21 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-0.71)[-0.708]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RWL_MAILSPIKE_GOOD(0.00)[209.85.210.42:from]; R_SPF_ALLOW(-0.20)[+ip4:209.85.128.0/17:c]; NEURAL_HAM_LONG(-1.03)[-1.032]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-fs@freebsd.org]; DMARC_NA(0.00)[freebsd.org]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; NEURAL_HAM_SHORT(-0.47)[-0.472]; RCPT_COUNT_TWO(0.00)[2]; RCVD_IN_DNSWL_NONE(0.00)[209.85.210.42:from]; FORGED_SENDER(0.30)[asomers@freebsd.org,asomers@gmail.com]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; ASN(0.00)[asn:15169, ipnet:209.85.128.0/17, country:US]; FROM_NEQ_ENVFROM(0.00)[asomers@freebsd.org,asomers@gmail.com]; FREEMAIL_ENVFROM(0.00)[gmail.com]; 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: Wed, 05 Aug 2020 15:24:55 -0000 On Wed, Aug 5, 2020 at 9:22 AM John Long via freebsd-fs < freebsd-fs@freebsd.org> wrote: > On 05/08/2020 13:15, Bob Friesenhahn wrote: > > On Tue, 4 Aug 2020, Karl Denninger wrote: > > > >> Let me give you two allegedly "degenerate" cases that are actually not > >> degenerate at all. > >> > >> 1. A laptop or workstation. It is backed up. It uses ZFS because > >> it's faster, and I can establish a filesystem for some project very > >> easily and quickly, it's segregated, I can work on it and destroy it > >> trivially when done. I can set quotas on that, etc. If I want to > >> move its mountpoint, I can trivially do so. And so on. Note that here > >> there is no redundancy at all; no raidZx, no mirroring, etc. I'm > >> merely using it for convenience. > > > > Did you remember to set copies=2 or copies=3 for zfs filesystems where > > you hope not to experience data loss? It needs to be set as soon as > > possible since it only applies to new files. This is a way to get more > > media redundancy, although the whole drive may fail. > > Does copies=n actually create n-1 additional physical copies or is it > copy-on-write, or something else yet? > > /jl > Yes, copies=3 will actually create 3 physical copies of the data somewhere. It's basically mirroring at the DMU layer, rather than the block layer. -Alan