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:
=================================
Preparing:
You'll need (or other media):
usb-flash
FreeBSD 7.1R DVD or FreeBSD-7.1R fixit cd
Backup data
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
Code:
$ gpt create -f ad0
You don't need to specify full path to device
2) Mount flash to /mnt
3) Create gpt boot partition
Code:
$ gpt boot -b /mnt/pmbr -g /mnt/gptboot ad0
by default this will create 64K partition, you can change this with -s and reduce to minimum (8K)
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)
Code:
$ gpt add -t ufs -s 268435456 ad0
5) To check what have you done
here's example output from one of my [already finished] test setup
Code:
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
in this table might be mistakes [writing by hand sux], later i made better lay-out
Partitions that you already have created are accessible as
/dev/ad0
p1 and /dev/ad0
p2
6) Create more partitions /usr (4GB) and /var (512MB) and /tmp (512MB)
Code:
$ gpt add -t ufs -s 10485760 ad0
$ gpt add -t ufs -s 1048576 ad0
$ gpt add -t ufs -s 1048576 ad0
7) Create 512MB swap
Code:
$ gpt add -t swap -s 1048576 ad0
8) Create home partition with remaining free space
Code:
$ gpt add -t ufs ad0
9) Format partitions
Code:
$ newfs -nL root /dev/ad0p2
$ newfs -nUL usr /dev/ad0p3
$ newfs -nUL var /dev/ad0p4
$ newfs -nUL tmp /dev/ad0p5
I like labeling partitions, because i don't need to edit /etc/fstab each time something changes
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
Code:
/dev/ufs/root / ufs rw 1 1
you need to edit your swap entry in fstab
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
Code:
options GEOM_PART_GPT # GUID Partition Tables.
For some reason, when i had all GEOM_PART_* in my kernel config i couldn't boot
common partition size cheat sheet
for megabytes:
sector count = 1024^2/512*MB_count
for gigabytes:
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
resources:
man gpt
EDIT:
made few inaccuracy fixes
Original thread
https://forums.freebsd.org/showthread.php?t=1305