guid partition table

GUID Partition TableGUID Partition Table

• Unified Extensible Firmware Interface (UEFI)

• GUID Partition Table (GPT)

• gpart(8)

• Root On ZFS

• FreeBSD9 – bsdinstall

• Soft-Update Journaling (SU+J)

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Unified Extensible Firmware InterfaceUnified Extensible Firmware Interface

BIOS limitations• 16-bit processor mode

• 1MB addressable space

UEFI advantages• UEFI v2.3.1 in April 2011

• Disk device compatibility (GUID Partition Table)

• Processor compatibility (x86, x64, ARM)

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GUID Partition Table – (1)GUID Partition Table – (1)

Limitation of MBR partition table• Partition record

active(1) 、 first CHS(3) 、 type(1) 、 last CHS(3) 、 start LBA(4) 、 size(4)

• Maximum capacity (232-1) x 512 bytes ~ 241 bytes = 2TBytes

GPT• Maximum capacity: 8ZBytes (273 bytes)

• Used on some BIOS system

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GPT• LBA 0: Legacy MBR

• LBA 1: GPT Header

• LBA 2~33: Partition Entries 128 partitions

• LBA 34~: Partitions

• LBA -34 ~ -1: Secondary GPT data

Misaligned block• SSD (1K LBA)

• WD (4K sector)

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Legacy MBR (LBA 0)• A single partition of type 0xEE, and of whole disk size (max 2T)

• For OSes which cannot read GPT: unknown partition, no space

• For GPT-aware OSes: check the “protective MBR”

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Partition header table (LBA 1)Offset Length Contents

0 8 bytes Signature ("EFI PART", 45 46 49 20 50 41 52 54)

8 4 bytesRevision (For GPT version 1.0 (through at least UEFI version 2.3.1), the value is 00 00 01 00)

12 4 bytes Header size in little endian (in bytes, usually 5C 00 00 00 meaning 92 bytes)16 4 bytes CRC32 of header (0 to header size), with this field zeroed during calculation20 4 bytes Reserved; must be zero24 8 bytes Current LBA (location of this header copy)32 8 bytes Backup LBA (location of the other header copy)40 8 bytes First usable LBA for partitions (primary partition table last LBA + 1)48 8 bytes Last usable LBA (secondary partition table first LBA - 1)56 16 bytes Disk GUID (also referred as UUID on UNIXes)72 8 bytes Partition entries starting LBA (always 2 in primary copy)80 4 bytes Number of partition entries84 4 bytes Size of a partition entry (usually 128)88 4 bytes CRC32 of partition array92 * Reserved; must be zeroes for the rest of the block (420 bytes for a 512-byte LBA)

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Partition header table (LBA 1)

# dd if=/dev/ada0 bs=512 count=1 skip=1 | hd00000000 45 46 49 20 50 41 52 54 00 00 01 00 5c 00 00 00 |EFI PART....\...|00000010 e6 f0 27 96 00 00 00 00 01 00 00 00 00 00 00 00 |..'.............|00000020 2f 60 38 3a 00 00 00 00 22 00 00 00 00 00 00 00 |/`8:....".......|00000030 0e 60 38 3a 00 00 00 00 7f a3 90 90 46 b4 de 11 |.`8:........F...|00000040 8e b8 00 21 85 12 22 74 02 00 00 00 00 00 00 00 |...!.."t........|00000050 80 00 00 00 80 00 00 00 e0 9d 1a 52 00 00 00 00 |...........R....|00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|*00000200

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Partition entries (LBA 2~33)• 128 bytes for each partition entry

Offset Length Contents

0 16 bytes Partition type GUID

16 16 bytes Unique partition GUID

32 8 bytes First LBA (little-endian)

40 8 bytes Last LBA (inclusive, usually odd)

48 8 bytes Attribute flags (e.g. bit 60 denotes read-only)

56 72 bytes Partition name (36 UTF-16LE code units)

128 Total

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Partition type GUID

freebsd-boot 83BD6B9D-7F41-11DC-BE0B-001560B84F0F

freebsd 516E7CB4-6ECF-11D6-8FF8-00022D09712B

freebsd-swap 516E7CB5-6ECF-11D6-8FF8-00022D09712B

freebsd-ufs 516E7CB6-6ECF-11D6-8FF8-00022D09712B

freebsd-vinum 516E7CB8-6ECF-11D6-8FF8-00022D09712B

freebsd-zfs 516E7CBA-6ECF-11D6-8FF8-00022D09712B

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FreeBSD – gpart (1)FreeBSD – gpart (1)

gpart(8)• Control utility for the disk partitioning GEOM class (ad0)

GEOM_PART_MBR (ad0 ad0s1)– GEOM_PART_BSD (ad0s1 ad0s1a)

GEOM_PART_GPT (ad0 ad0p1)

• gpart create -s mbr ad0 gpart add -t freebsd ad0 (ad0 ad0s1) gpart create -s bsd ad0s1

• gpart create -s gpt ad0

• gpart destroy [ -F ] ad0 -F: forced destroying of the partition table

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gpart(8)• gpart add -t type [ … ] ad0

type: freebsd-boot, freebsd-swap, freebsd-ufs, freebsd-zfs, freebsd -b start -s size -a alignment: -a 4k for 4K-sector HDD -i index -l label: used on partitioning schemes that support partition labels

• gpart delete –i index ad0

• gpart show [ -l | -r ] [ -p ] ad0 -l: print partition labels instead of partition type -r: show GUID -p: show provider names instead of partition indexes

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gpart(8)• gpart bootcode [ -b bootcode ] [ -p partcode -i index ] ad0

-b: embed bootstrap code into the partitioning scheme’s metadata -p: write bootstrap code into a partition Bootstraping for MBR scheme

– /boot/mbr or /boot/boot0 in partition table’s metadata» /boot/mbr searches partition with active attribute

» /boot/boot0 has a boot manager

– /boot/boot in BSD partition table’s metadata

Bootstraping for GPT scheme– /boot/pmbr in the first disk sector (Protective MBR)

» /boot/pmbr searches the freebsd-boot partition

– /boot/gptboot or /boot/gptzfsboot in freebsd-boot partition» /boot/gptboot searches the freebsd-ufs partition to run /boot/loader

» /boot/gptzfsboot searches the freebsd-zfs partition to run /boot/zfsloader

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gpart(8)• gpart modify -i index [ -l label ] [ -t type ] ad0

• gpart resize -i index [ -a alignment ] [ -s size ] ad0

• gpart { set | unset } -a attrib -i index ad0 Set "Active" for MBR scheme

– gpart set -a active –i 1 ad0

• gpart { backup | restore } ad0

• gpart recover ad0 GPT-only

• gpart { command … -f x | commit | undo } ad0

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Root On ZFS – (1)Root On ZFS – (1)

Root On ZFS• Using MBR disk

UFS /boot FreeBSD-ZFS partition in a FreeBSD MBR slice

– dd if=/mnt2/boot/zfsboot of=/dev/ad0s3 count=1

– dd if=/mnt2/boot/zfsboot of=/dev/ad0s3a skip=1 seek=1024

FreeBSD MBR slice– Fails to boot

• Using GPT disk Disadvantage

– Can’t dual boot using FreeBSD commercial bootcode

– Using GPT-aware grub setup and hybrid GPT/MBR

http://wiki.freebsd.org/RootOnZFS now for 8.x• 9.0 http://www.aisecure.net/2011/05/01/root-on-zfs-freebsd-current/

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Creating a bootable ZFS Filesystem• Create GPT disk

gpart create -s gpt ad0

• Create the boot, swap and zfs partitions gpart add -s 64k -t freebsd-boot ad0 gpart add -s 4g -t freebsd-swap -l swap0 ad0 gpart add -t freebsd-zfs -l disk0 ad0

• Install the Protected MBR (pmbr) and gptzfsboot loader gpart bootcode -b pmbr -p gptzfsboot -i 1 ad0

• Load ZFS kernel module kldload zfs

• Create ZFS Pool zroot zpool create zroot /dev/gpt/disk0 zpool set bootfs=zroot zroot

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Installing FreeBSD to the ZFS filesystem• Create ZFS filesystem hierarchy

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Installing FreeBSD to the ZFS filesystem• Install FreeBSD to zroot

Manually install base, kernel(s), lib32, games, doc, …

• Make /var/empty readonly zfs set readonly=on zroot/var/empty

• Manually configure chroot /etc/rc.conf

– hostname, networks, zfs_enable, sshd, ntpd, …

/boot/loader.conf– zfs_load, vfs.root.mountfrom

root password Time zone …

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Installing FreeBSD to the ZFS filesystem• Install zpool.cache to the ZFS filesystem

zpool export zroot zpool import –o cachefile=/tmp/zpool.cache zroot Copy /tmp/zpool.cache into zroot/boot/zfs/

Finish install• Create /etc/fstab

swap

• Set mount points for zfs filesystems zfs set mountpoint=blah zroot/blah Alternatively, you can specify these in /etc/fstab

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gpart show

swapinfo

# gpart show=> 34 83886013 ada0 GPT (40G) 34 128 1 freebsd-boot (64k) 162 4194304 2 freebsd-swap (2.0G) 4194466 79691581 3 freebsd-zfs (38G)# swapinfoDevice 1K-blocks Used Avail Capacity/dev/gpt/swap0 2097152 0 2097152 0%

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zpool status -v# zpool status -v pool: zroot state: ONLINE scan: none requestedconfig:

NAME STATE READ WRITE CKSUM zroot ONLINE 0 0 0 ada0p3 ONLINE 0 0 0

errors: No known data errors

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zfs list# zfs listNAME USED AVAIL REFER MOUNTPOINTzroot 657M 36.5G 344M legacyzroot/home 31K 36.5G 31K legacyzroot/tmp 36K 36.5G 36K /tmpzroot/usr 311M 36.5G 311M /usrzroot/usr/ports 95K 36.5G 33K /usr/portszroot/usr/ports/distfiles 31K 36.5G 31K /usr/ports/distfileszroot/usr/ports/packages 31K 36.5G 31K /usr/ports/packageszroot/usr/src 31K 36.5G 31K /usr/srczroot/var 461K 36.5G 126K /varzroot/var/crash 31.5K 36.5G 31.5K /var/crashzroot/var/db 116K 36.5G 85K /var/dbzroot/var/db/pkg 31K 36.5G 31K /var/db/pkgzroot/var/empty 31K 36.5G 31K /var/emptyzroot/var/log 45K 36.5G 45K /var/logzroot/var/mail 31K 36.5G 31K /var/mailzroot/var/run 48.5K 36.5G 48.5K /var/runzroot/var/tmp 32K 36.5G 32K /var/tmp

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mount

# mountzroot on / (zfs, local, noatime)devfs on /dev (devfs, local, multilabel)zroot/tmp on /tmp (zfs, local, nosuid)zroot/usr on /usr (zfs, local, noatime)zroot/usr/ports on /usr/ports (zfs, local, noatime, nosuid)zroot/usr/ports/distfiles on /usr/ports/distfiles (zfs, local, noatime, noexec, nosuid)zroot/usr/ports/packages on /usr/ports/packages (zfs, local, noatime, noexec, nosuid)zroot/usr/src on /usr/src (zfs, local, noatime, noexec, nosuid)zroot/var on /var (zfs, local, noatime)zroot/var/crash on /var/crash (zfs, local, noatime, noexec, nosuid)zroot/var/db on /var/db (zfs, local, noatime, noexec, nosuid)zroot/var/db/pkg on /var/db/pkg (zfs, local, noatime, nosuid)zroot/var/empty on /var/empty (zfs, local, noatime, noexec, nosuid, read-only)zroot/var/log on /var/log (zfs, local, noatime, noexec, nosuid)zroot/var/mail on /var/mail (zfs, local, noatime, noexec, nosuid)zroot/var/run on /var/run (zfs, local, noatime, noexec, nosuid)zroot/var/tmp on /var/tmp (zfs, local, nosuid)

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bsdinstall (FreeBSD 9) – (1)bsdinstall (FreeBSD 9) – (1)

http://www.freebsd.org/doc/handbook/bsdinstall.html

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Install 、 Shell 、 Live CD

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Setting hostname

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Selecting components to install

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Partitioning methods• Shell – gpart(8) 、 fdisk(8) 、 bsdlabel(8)

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Guided Partitioning• Select disk

• Replace { ad | da } by ada

• { ad | da }’s are linkedto ada’s

• How to partition the disk Entire Disk Partition – use free space

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Guided Partitioning result

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Manual Partitioning

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Choose a partitioning scheme• GPT 、 MBR

• DON’T use BSD!!!

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Add partitions• freebsd-boot

FreeBSD boot code. This partition must be first on the disk.

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Final confirmation

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Fetching Checksum Verification Extraction

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Post-installation• root password

• Network interfaces Wired – Static IPv4 / DHCP / Static IPv6 / SLAAC Wireless DNS

• Time Zone

• Services

• Add users

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Final configuration

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Soft Updates Journaling – (1)Soft Updates Journaling – (1)

To maintain filesystem metadata consistency• Synchronous write

• Non-Volatile RAM

• Journaling

• COW

• Soft Updates

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Ordering constrains• Name in on-disk directory must be deleted

• Deallocate on-disk inode

• Release file’s blocks to free-space bitmap

Soft Updates• Dependency structures

Only inconsistencies• Blocks marked in use that are free

• Inodes marked in use that are free

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Soft Updates Journaling (SUJ, SU+J)• Only need to journal operations that orphan resources

Increased link count Decreased link count …

• Need a maximum 16Mb .sujournal (a 32Mb file…)

• Recovery steps Scan the journal Modify link counts Free inodes with zero count or unlinked Free unallocated blocks

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First appeared in 9.0-CURRENT (r207141) in April 2010• Now 9.0-RC3 …

Enable SU+J• newfs –j …

tunefs –j { enable | disable } for SUJ

• Different from gjournal (-J) tunefs –J { enable | disable } for gjournal

guid partition table

Documents

partition entries lba

unknown partition

single partition of

legacy mbr lba

bytesdisk guid

armcomputer center

sectorcomputer center

gpt version