From owner-freebsd-questions@freebsd.org Thu Jan 18 05:14:33 2018 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A8EE7EA757E for ; Thu, 18 Jan 2018 05:14:33 +0000 (UTC) (envelope-from vas@mpeks.tomsk.su) Received: from relay2.tomsk.ru (mail.sibptus.tomsk.ru [212.73.124.5]) by mx1.freebsd.org (Postfix) with ESMTP id 123DB784D8 for ; Thu, 18 Jan 2018 05:14:32 +0000 (UTC) (envelope-from vas@mpeks.tomsk.su) X-Virus-Scanned: by clamd daemon 0.98.5_1 for FreeBSD at relay2.tomsk.ru Received: from [212.73.125.240] (HELO admin.sibptus.transneft.ru) by relay2.tomsk.ru (CommuniGate Pro SMTP 5.1.16) with ESMTPS id 39915158; Thu, 18 Jan 2018 11:09:40 +0600 Received: from admin.sibptus.transneft.ru (sudakov@localhost [127.0.0.1]) by admin.sibptus.transneft.ru (8.15.2/8.15.2) with ESMTP id w0I5EQ1x094908; Thu, 18 Jan 2018 12:14:28 +0700 (+07) (envelope-from vas@mpeks.tomsk.su) Received: (from sudakov@localhost) by admin.sibptus.transneft.ru (8.15.2/8.15.2/Submit) id w0I5EOTo094905; Thu, 18 Jan 2018 12:14:24 +0700 (+07) (envelope-from vas@mpeks.tomsk.su) X-Authentication-Warning: admin.sibptus.transneft.ru: sudakov set sender to vas@mpeks.tomsk.su using -f Date: Thu, 18 Jan 2018 12:14:23 +0700 From: Victor Sudakov To: Trond Endrest?l Cc: FreeBSD questions Subject: Re: Dualboot and ZFS Message-ID: <20180118051423.GA94227@admin.sibptus.transneft.ru> References: <20180115051308.GA45168@admin.sibptus.transneft.ru> <20180115125241.GB60956@admin.sibptus.transneft.ru> <20180115144747.GA65526@admin.sibptus.transneft.ru> <20180115151526.GA66342@admin.sibptus.transneft.ru> <20180116034929.GB89443@admin.sibptus.transneft.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: AO "Svyaztransneft", SibPTUS X-PGP-Key: http://www.dreamwidth.org/pubkey?user=victor_sudakov X-PGP-Fingerprint: 10E3 1171 1273 E007 C2E9 3532 0DA4 F259 9B5E C634 User-Agent: Mutt/1.9.1 (2017-09-22) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Jan 2018 05:14:33 -0000 Trond Endrest?l wrote: > [script]# sysctl vfs.zfs.min_auto_ashift=12 > vfs.zfs.min_auto_ashift: 9 -> 12 Why do you change this? "Min ashift used when creating new top-level vdevs", hmm. You probably know something I don't. [dd] > > !!! Write the boot manager to the boot block in the MBR !!! > > [script]# gpart bootcode -b /boot/boot0 /dev/ada0 > bootcode written to ada0 Fine, here you install the bootmanager into the MBR. However I have a couple of questions below regarding the VBR. > > !!! Write /boot/zfsboot as two separate pieces to /dev/ada0s3{,a} !!! > > [script]# dd if=/boot/zfsboot of=/tmp/zfsboot1 count=1 > 1+0 records in > 1+0 records out > 512 bytes transferred in 0.000383 secs (1337758 bytes/sec) > [script]# gpart bootcode -b /tmp/zfsboot1 /dev/ada0s3 > bootcode written to ada0s3 Why do you need this trick with /tmp/zfsboot1 ? Why not sysctl kern.geom.debugflags=0x10 dd if=/boot/zfsboot of=/dev/ada0s3 count=1 The example in zfsboot(8) is even weirder. They create a BSD label within an MBR slice, but never any partitions within. Why do they do it like that? Quoting the manual page: gpart create -s BSD ada0s1 gpart bootcode -b /boot/boot0 ada0 gpart set -a active -i 1 ada0 dd if=/boot/zfsboot of=/dev/ada0s1 count=1 dd if=/boot/zfsboot of=/dev/ada0s1 iseek=1 oseek=1024 > [script]# dd if=/boot/zfsboot of=/dev/ada0s3a skip=1 seek=1024 > 128+0 records in > 128+0 records out > 65536 bytes transferred in 0.043591 secs (1503439 bytes/sec) Should the "of=" target here be ada0s3a or just ada0s3 ? -- Victor Sudakov, VAS4-RIPE, VAS47-RIPN AS43859