[DEPRECATED] FreeBSD [GUID] GPT howto
The next hot thing after 7.1R is GPT
old limit of 4 partitions is finally history
with GUID Partition table you can have up to 128 partitions.
Should i also say, that GPT will easily handle partitions over 2TB
MBR had problems with that
As soon as i heard [thanks to nsayers post]that it's possible to boot FreeBSD from GPT i had to test it
I have encountered some problems that i resolved on my own.
That's why i'm making this howto, so you don't have to spend few hours, just because something went wrong.
OK, here we go:
You'll need (or other media):
FreeBSD 7.1R DVD or FreeBSD-7.1R fixit cd
During process we will delete all data on HDD, so
backup your valuable data and system, if you already have 7.1R on your PC
If you don't you need to upgrade your system to 7.1 [dunno if GPT works with 6.4]
before and after upgrading backup all data
I suggest you use GENERIC kernel, if you won't have right option, you can create system on GPT, but you can't boot it [another my fallback]
Copy necessary data
You need to make copy of /boot/pmbr and /boot/gptboot
because they are not on disks and this was my fallback nr1
You will need these files later.
I will copy them to my usb-flash
Once you have copied these files to some where, where you can get them, reboot in fixit mode [use cd]
Creating GUID partition tables
1) Erase MBR and write GPT table
$ gpt create -f ad0
2) Mount flash to /mnt
3) Create gpt boot partition
$ gpt boot -b /mnt/pmbr -g /mnt/gptboot ad0
value behind argument -s must be size in sectors
1 sector is 512B
I suggest no changing it, who know if in 7.2 size might change
Also don't improvise to much, make sure boot partition is Nr 1 and root partition is Nr 2, otherwise you can't boot at all [another my fallback]
Note that when i say boot partition it doesn't mean /boot, it's different. /boot is in same partition as root
4) Create root partition (i'll make 256MB)
$ gpt add -t ufs -s 268435456 ad0
$ gpt show ad0
fixit# gpt show ad0 start size index content 0 1 PMBR 1 1 Pri GPT header 2 32 Pri GPT table 34 128 1 GPT part - FreeBSD boot 162 1048576 2 GPT part - FreeBSD UFS/UFS2 1048738 2097152 3 GPT part - FreeBSD UFS/UFS2 3145890 2097152 5 GPT part - FreeBSD UFS/UFS2 5243042 1048576 6 GPT part - FreeBSD UFS/UFS2 16777378 6291456 7 GPT part - FreeBSD UFS/UFS2 23068834 168926701 11 GPT part - FreeBSD UFS/UFS2 191995535 10485760 10 GPT part - FreeBSD UFS/UFS2 202401295 109051904 9 GPT part - FreeBSD UFS/UFS2 311533199 1048576 8 GPT part - FreeBSD swap 312581775 32 Sec GPT table 312581807 1 Sec GPT header
Partitions that you already have created are accessible as
/dev/ad0p1 and /dev/ad0p2
6) Create more partitions /usr (4GB) and /var (512MB) and /tmp (512MB)
$ gpt add -t ufs -s 10485760 ad0 $ gpt add -t ufs -s 1048576 ad0 $ gpt add -t ufs -s 1048576 ad0
$ gpt add -t swap -s 1048576 ad0
$ gpt add -t ufs ad0
$ newfs -nL root /dev/ad0p2 $ newfs -nUL usr /dev/ad0p3 $ newfs -nUL var /dev/ad0p4 $ newfs -nUL tmp /dev/ad0p5
It's also easier to track partitions if you got many of them
10) Mount root and run restore, then mount and restore usr, var and home.
After you're done, if you didn't use labels edit /etc/fstab
remember labels are placed in /dev/ufs/ directory
so for root it would look something like
/dev/ufs/root / ufs rw 1 1
when you create partition without using -i key, which is used to change partition NR, GPT will start with 1 and increment automatically.
so in this example swap will be /dev/ad0p5
and /home will be /dev/ad0p6
After you're done you can unmount partitions and reboot system.
It should boot with GENERIC.
If not, post here, I can resolve problems... like i did when i had to on my PC
Note also that you don't need to create bsdlabels anymore
TIP: it's also very easy to set up swap on most outer tracks of HDD if you're interested in this look at -b parameter in manual
kernel options [make sure you have this in kernel config
options GEOM_PART_GPT # GUID Partition Tables.
common partition size cheat sheet
sector count = 1024^2/512*MB_count
sector count = 1024^3/512*GB_count
8KB = 16 sectors
32KB = 64 sect
64KB = 128 sect
256MB = 524288 sect
512MB = 1048576 sect
1GB = 2097152 sect
2GB = 4194304 sect
5GB = 10485760 sect
10GB = 20971520 sect
If there's anything unclear please ask, i will answer and explain
made few inaccuracy fixes
Last edited by graudeejs; 19th December 2010 at 07:14 PM.
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