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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
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2020-12-20 02:59:44 +00:00
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@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 10, 2015
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.Dd July 25, 2016
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.Dt GPART 8
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.Os
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.Sh NAME
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@ -1193,86 +1193,112 @@ Otherwise the values will be left unchanged.
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.Sh EXIT STATUS
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Exit status is 0 on success, and 1 if the command fails.
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.Sh EXAMPLES
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Create a GPT scheme on
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.Pa ada0 :
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The examples below assume that the disk's logical block size is 512
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bytes, regardless of its physical block size.
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.Ss GPT
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In this example, we will format
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.Pa ada0
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with the GPT scheme and create boot, swap and root partitions.
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First, we need to create the partition table:
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.Bd -literal -offset indent
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/sbin/gpart create -s GPT ada0
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.Ed
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.Pp
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Embed GPT bootstrap code into a protective MBR:
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Next, we install a protective MBR with the first-stage bootstrap code.
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The protective MBR lists a single, bootable partition spanning the
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entire disk, thus allowing non-GPT-aware BIOSes to boot from the disk
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and preventing tools which do not understand the GPT scheme from
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considering the disk to be unformatted.
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.Bd -literal -offset indent
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/sbin/gpart bootcode -b /boot/pmbr ada0
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.Ed
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.Pp
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Create a dedicated
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We then create a dedicated
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.Cm freebsd-boot
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partition that can boot
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partition to hold the second-stage boot loader, which will load the
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.Fx
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from a
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.Cm freebsd-ufs
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partition, and install bootstrap code into it.
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kernel and modules from a UFS or ZFS filesystem.
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This partition must be larger than the bootstrap code
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.Po
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usually either
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either
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.Pa /boot/gptboot
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or
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for UFS or
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.Pa /boot/gptzfsboot
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for ZFS
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.Pc ,
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but smaller than 545 kB since the first-stage loader will load the
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entire partition into memory during boot, regardless of how much data
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it actually contains.
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This example uses 88 blocks (44 kB) so the next partition will be
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aligned on a 64 kB boundary without the need to specify an explicit
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offset or alignment.
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The boot partition itself is aligned on a 4 kB boundary.
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We create a 472-block (236 kB) boot partition at offset 40, which is
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the size of the partition table (34 blocks or 17 kB) rounded up to the
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nearest 4 kB boundary.
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.Bd -literal -offset indent
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/sbin/gpart add -b 40 -s 88 -t freebsd-boot ada0
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/sbin/gpart add -b 40 -s 472 -t freebsd-boot ada0
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/sbin/gpart bootcode -p /boot/gptboot -i 1 ada0
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.Ed
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.Pp
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Create a 512MB-sized
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.Cm freebsd-ufs
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partition to contain a UFS filesystem from which the system can boot.
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We now create a 4 GB swap partition at the first available offset,
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which is 40 + 472 = 512 blocks (256 kB).
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.Bd -literal -offset indent
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/sbin/gpart add -s 512M -t freebsd-ufs ada0
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/sbin/gpart add -s 4G -t freebsd-swap ada0
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.Ed
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.Pp
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Create an MBR scheme on
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.Pa ada0 ,
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then create a 30GB-sized
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.Fx
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slice, mark it active and
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install the
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.Nm boot0
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boot manager:
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Aligning the swap partition and all subsequent partitions on a 256 kB
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boundary ensures optimal performance on a wide range of media, from
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plain old disks with 512-byte blocks, through modern
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.Dq advanced format
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disks with 4096-byte physical blocks, to RAID volumes with stripe
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sizes of up to 256 kB.
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.Pp
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Finally, we create and format an 8 GB
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.Cm freebsd-ufs
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partition for the root filesystem, leaving the rest of the slice free
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for additional filesystems:
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.Bd -literal -offset indent
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/sbin/gpart add -s 8G -t freebsd-ufs ada0
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/sbin/newfs -Uj /dev/ada0p3
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.Ed
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.Ss MBR
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In this example, we will format
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.Pa ada0
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with the MBR scheme and create a single partition which we subdivide
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using a traditional
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.Bx
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disklabel.
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.Pp
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First, we create the partition table and a single 64 GB partition,
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then we mark that partition active (bootable) and install the
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first-stage boot loader:
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.Bd -literal -offset indent
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/sbin/gpart create -s MBR ada0
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/sbin/gpart add -t freebsd -s 30G ada0
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/sbin/gpart add -t freebsd -s 64G ada0
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/sbin/gpart set -a active -i 1 ada0
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/sbin/gpart bootcode -b /boot/boot0 ada0
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.Ed
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.Pp
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Now create a
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.Bx
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scheme
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.Pf ( Bx
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label) with space for up to 20 partitions:
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Next, we create a disklabel in that partition
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.Po
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.Dq slice
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in disklabel terminology
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.Pc
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with room for up to 20 partitions:
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.Bd -literal -offset indent
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/sbin/gpart create -s BSD -n 20 ada0s1
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.Ed
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.Pp
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Create a 1GB-sized UFS partition and a 4GB-sized swap partition:
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We then create an 8 GB root partition and a 4 GB swap partition:
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.Bd -literal -offset indent
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/sbin/gpart add -t freebsd-ufs -s 1G ada0s1
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/sbin/gpart add -t freebsd-ufs -s 8G ada0s1
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/sbin/gpart add -t freebsd-swap -s 4G ada0s1
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.Ed
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.Pp
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Install bootstrap code for the
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Finally, we install the appropriate boot loader for the
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.Bx
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label:
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.Bd -literal -offset indent
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/sbin/gpart bootcode -b /boot/boot ada0s1
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.Ed
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.Ss VTOC8
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.Pp
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Create a VTOC8 scheme on
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.Pa da0 :
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@ -1298,6 +1324,7 @@ After creating all required partitions, embed bootstrap code into them:
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.Bd -literal -offset indent
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/sbin/gpart bootcode -p /boot/boot1 da0
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.Ed
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.Ss Backup and Restore
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.Pp
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Create a backup of the partition table from
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.Pa da0 :
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