Date: Mon, 25 Jul 2016 11:25:34 +0000 (UTC) From: =?UTF-8?Q?Dag-Erling_Sm=c3=b8rgrav?= <des@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r303289 - head/sbin/geom/class/part Message-ID: <201607251125.u6PBPYWa076837@repo.freebsd.org>
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Author: des Date: Mon Jul 25 11:25:33 2016 New Revision: 303289 URL: https://svnweb.freebsd.org/changeset/base/303289 Log: Rewrite the GPT and MBR examples. For GPT, ensure that the boot partition is large enough for gptzfsboot, which has doubled in size since 10. PR: 211361 MFC after: 3 days Modified: head/sbin/geom/class/part/gpart.8 Modified: head/sbin/geom/class/part/gpart.8 ============================================================================== --- head/sbin/geom/class/part/gpart.8 Mon Jul 25 09:12:08 2016 (r303288) +++ head/sbin/geom/class/part/gpart.8 Mon Jul 25 11:25:33 2016 (r303289) @@ -24,7 +24,7 @@ .\" .\" $FreeBSD$ .\" -.Dd December 10, 2015 +.Dd July 25, 2016 .Dt GPART 8 .Os .Sh NAME @@ -1193,86 +1193,112 @@ Otherwise the values will be left unchan .Sh EXIT STATUS Exit status is 0 on success, and 1 if the command fails. .Sh EXAMPLES -Create a GPT scheme on -.Pa ada0 : +The examples below assume that the disk's logical block size is 512 +bytes, regardless of its physical block size. +.Ss GPT +In this example, we will format +.Pa ada0 +with the GPT scheme and create boot, swap and root partitions. +First, we need to create the partition table: .Bd -literal -offset indent /sbin/gpart create -s GPT ada0 .Ed .Pp -Embed GPT bootstrap code into a protective MBR: +Next, we install a protective MBR with the first-stage bootstrap code. +The protective MBR lists a single, bootable partition spanning the +entire disk, thus allowing non-GPT-aware BIOSes to boot from the disk +and preventing tools which do not understand the GPT scheme from +considering the disk to be unformatted. .Bd -literal -offset indent /sbin/gpart bootcode -b /boot/pmbr ada0 .Ed .Pp -Create a dedicated +We then create a dedicated .Cm freebsd-boot -partition that can boot +partition to hold the second-stage boot loader, which will load the .Fx -from a -.Cm freebsd-ufs -partition, and install bootstrap code into it. +kernel and modules from a UFS or ZFS filesystem. This partition must be larger than the bootstrap code .Po -usually either +either .Pa /boot/gptboot -or +for UFS or .Pa /boot/gptzfsboot +for ZFS .Pc , but smaller than 545 kB since the first-stage loader will load the entire partition into memory during boot, regardless of how much data it actually contains. -This example uses 88 blocks (44 kB) so the next partition will be -aligned on a 64 kB boundary without the need to specify an explicit -offset or alignment. -The boot partition itself is aligned on a 4 kB boundary. +We create a 472-block (236 kB) boot partition at offset 40, which is +the size of the partition table (34 blocks or 17 kB) rounded up to the +nearest 4 kB boundary. .Bd -literal -offset indent -/sbin/gpart add -b 40 -s 88 -t freebsd-boot ada0 +/sbin/gpart add -b 40 -s 472 -t freebsd-boot ada0 /sbin/gpart bootcode -p /boot/gptboot -i 1 ada0 .Ed .Pp -Create a 512MB-sized +We now create a 4 GB swap partition at the first available offset, +which is 40 + 472 = 512 blocks (256 kB). +.Bd -literal -offset indent +/sbin/gpart add -s 4G -t freebsd-swap ada0 +.Ed +.Pp +Aligning the swap partition and all subsequent partitions on a 256 kB +boundary ensures optimal performance on a wide range of media, from +plain old disks with 512-byte blocks, through modern +.Dq advanced format +disks with 4096-byte physical blocks, to RAID volumes with stripe +sizes of up to 256 kB. +.Pp +Finally, we create and format an 8 GB .Cm freebsd-ufs -partition to contain a UFS filesystem from which the system can boot. +partition for the root filesystem, leaving the rest of the slice free +for additional filesystems: .Bd -literal -offset indent -/sbin/gpart add -s 512M -t freebsd-ufs ada0 +/sbin/gpart add -s 8G -t freebsd-ufs ada0 +/sbin/newfs -Uj /dev/ada0p3 .Ed +.Ss MBR +In this example, we will format +.Pa ada0 +with the MBR scheme and create a single partition which we subdivide +using a traditional +.Bx +disklabel. .Pp -Create an MBR scheme on -.Pa ada0 , -then create a 30GB-sized -.Fx -slice, mark it active and -install the -.Nm boot0 -boot manager: +First, we create the partition table and a single 64 GB partition, +then we mark that partition active (bootable) and install the +first-stage boot loader: .Bd -literal -offset indent /sbin/gpart create -s MBR ada0 -/sbin/gpart add -t freebsd -s 30G ada0 +/sbin/gpart add -t freebsd -s 64G ada0 /sbin/gpart set -a active -i 1 ada0 /sbin/gpart bootcode -b /boot/boot0 ada0 .Ed .Pp -Now create a -.Bx -scheme -.Pf ( Bx -label) with space for up to 20 partitions: +Next, we create a disklabel in that partition +.Po +.Dq slice +in disklabel terminology +.Pc +with room for up to 20 partitions: .Bd -literal -offset indent /sbin/gpart create -s BSD -n 20 ada0s1 .Ed .Pp -Create a 1GB-sized UFS partition and a 4GB-sized swap partition: +We then create an 8 GB root partition and a 4 GB swap partition: .Bd -literal -offset indent -/sbin/gpart add -t freebsd-ufs -s 1G ada0s1 +/sbin/gpart add -t freebsd-ufs -s 8G ada0s1 /sbin/gpart add -t freebsd-swap -s 4G ada0s1 .Ed .Pp -Install bootstrap code for the +Finally, we install the appropriate boot loader for the .Bx label: .Bd -literal -offset indent /sbin/gpart bootcode -b /boot/boot ada0s1 .Ed +.Ss VTOC8 .Pp Create a VTOC8 scheme on .Pa da0 : @@ -1298,6 +1324,7 @@ After creating all required partitions, .Bd -literal -offset indent /sbin/gpart bootcode -p /boot/boot1 da0 .Ed +.Ss Backup and Restore .Pp Create a backup of the partition table from .Pa da0 :
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