Firstly we need to make virtual device for our iso image (use mdconfig for it):
howtobsd# mdconfig -a -f /path_to_iso/Mac_OS_X.iso
md0

md0 (command return) – it is name of virtual device (should appear in /dev/md0).
you can check if it appeared in /dev:
howtobsd# ls /dev/ | grep md0
md0

And now we just need to mount virtual device:

howtobsd# mount_cd9660 /dev/md0 /cdrom

That’s all, your iso image available in /cdrom directory.

If you need to unmount and delete virtual device, do following commands:
howtobsd# umount /cdrom
mdconfig -d -u md0

You can check your smart data using utility smartmontools:

howtobsd# smartctl -a /dev/ad0 | grep Load_Cycle_Count
193 Load_Cycle_Count 0x0032 099 099 000 Old_age Always - 37104

37104 – it is a number of parking (only imagine it! On my laptop before fixing this value had been increased on 50 numbers per\hour)

For prevent hdd from  head parking or change timeout you can use ataidle.

howtobsd# cd /usr/ports/sysutils/ataidle/
howtobsd# make install clean
howtobsd# ataidle -P 254 /dev/ad0

This commands set APM (Advanced Power Management) to highest power consumption.

and add into rc.conf:
ataidle_enable="YES"
ataidle_devices="ad0"
ataidle_ad0="-I 60 -S 120 -A 127 -P 254"

#smartctl -a /dev/ad1

This command show you many various indicatos about your disk (rate of hardware read errors, count of reallocated sectors, hdd temperature etc)

You also can run smartd daemon with will ask disks one time per 30minutes

#cp /usr/local/etc/smartd.conf.sample /usr/local/etc/smartd.conf
#vim /usr/local/etc/smartd.conf:
/dev/ad0 -S on -o on -a -I 194 -m admin@howtobsd.com
/dev/ad4 -S on -o on -a -I 194 -m admin@howtobsd.com

add to /etc/rc.conf:

usr/local/etc/>echo 'smartd_enable="YES"' >> /etc/rc.conf
/usr/local/etc/>echo 'smartd_flags="-l local2 --interval=300"' >> /etc/rc.conf

#/usr/local/etc/rc.d/smartd start

That is all!

1)Shut down your FreeBSD:
#halt

and swich off computer from power

2)Connect your new hdd, swich on computer and make shure that hdd is detected (in BIOS) and start booting system.
3)For example your new hdd has detected like this: /dev/ad4
4)make directories for points for mounting yours partitions:

#mkdir /mnt/root && mkdir /mnt/var && mkdir /mnt/usr

5) Start up sysinstall program:
#sysinstall
choose Configure-> Fdisk-> ad4 (carefully)
create freeBSD slice on the all disk space. Press s (set bootable), press w (write changes). And choose “Standard Install a standard MBR” and press “YES”
Go to the Label choose ad4 press ‘a’ (auto-defaults for all), it is auto create partitions for you. You can create partitions yourself (if you need special partition size). After that you have to select mount points. For every partition press ‘m’ and insert mount point (for exemple in my partition ad4s1e mount point “/mnt/usr”), when you finish, press ‘w’ (write changes). If you create partitions by hand – you should be shure that your root partition has created with letter “a” like this: ad4s1a. You can obtain it in thw next trick. Firstly create partinion with mount point ‘/’ – only in this case partition will be created by Label with letter ‘a’. And after that you need change mount point partition ad4s1a in ‘/mnt/root/’. I advise you create partition the same in your previous disk (see in /etc/fstab). Don’t forget create partitions that were in your previous disk (/tmp and others) After that program create partitions and mount it in your points – /mnt/root, /mnt/var, mkdir /mnt/usr.

6) Check your partition and mount points:
#df
7) Now you are ready for magic commands:
# cd / ; pax -p eme -X -rw . /mnt/root
# cd /var; pax -p eme -X -rw . /mnt/var
# cd /usr; pax -p eme -X -rw . /mnt/usr

8)If letters partitions in your new hdd are not conform with letters partitions your previous hdd you must fix it in you new fstab: /mnt/root/etc/fstab
Carefully examine your fstab and output df. If your new hdd take the place of previous hdd (replace) and letters of partitions the same in the both hdds. You don’t have to change mnt/root/etc/fstab, becose when you replace you old hdd pertition will be correct for you new hdd. But if your partitions were changed – edit /mnt/root/etc/fstab. For example if partiotion /var has lable /dev/ad0s1f and became /dev/ad0s1g you have to change in /mnt/root/etc/fstab from ad0s1f to ad0s1g

9)Shut down…swich off… replace hdd..swich on…enjoy

I did RAID-1 on the FreeBSD 7.1-RELEASE with two identical HDD – WD15EARS (1,5Tb)
I think you can use any hhd on condition that firs device have to be smoller size than second.

in my case:
- FreeBSD detect it as ad10 and ad16
- System has been installed in ad10 (with standard boot loader)

Before starting you have to do this:
howtobsd#sysctl kern.geom.debugflags=16

next you can add you device where has installed your system (In my situation it is ad10)

howtobsd#gmirror label -v -b round-robin gm0 /dev/ad10
Metadata value stored on /dev/ad10.
Done.

and add kernels module gmirror:

howtobsd#echo geom_mirror_load="YES" >> /boot/loader.conf

I’d advice you to backup your current version of fstab before editing:

howtobsd#cp /etc/fstab /etc/fstab.backup

edit your fstab-file very carefully.
howtobsd#vim /etc/fstab

you have to change /dev/ad10xxx on /dev/mirror/gm0xxx – (very carefully! you mustn’t forget “/mirror“)

my fstab before:
# Device Mountpoint FStype Options Dump Pass#
/dev/ad10s1b none swap sw 0 0
/dev/ad10s1a / ufs rw 1 1
/dev/ad10s1d /tmp ufs rw 2 2
/dev/ad10s1e /usr ufs rw 2 2
/dev/ad10s1f /var ufs rw 2 2
/dev/ad10s1g /vol1 ufs rw 2 2
/dev/ad10s1h /vol2 ufs rw,userquota 2 2

my fstab after:
# Device Mountpoint FStype Options Dump Pass#
/dev/mirror/gm0s1b none swap sw 0 0
/dev/mirror/gm0s1a / ufs rw 1 1
/dev/mirror/gm0s1d /tmp ufs rw 2 2
/dev/mirror/gm0s1e /usr ufs rw 2 2
/dev/mirror/gm0s1f /var ufs rw 2 2
/dev/mirror/gm0s1g /vol1 ufs rw 2 2
/dev/mirror/gm0s1h /vol2 ufs rw,userquota 2 2

going to reboot

and finally add second hdd in raid massive:

howtobsd#gmirror insert gm0 /dev/ad16

at this moment system started background mirroring
you can check status of rebuilding:
howtobsd# gmirror status
Name Status Components
mirror/gm0 DEGRADED ad10
ad16 (0%)

or more verbose:

howtobsd# gmirror list
Geom name: gm0
State: DEGRADED
Components: 2
Balance: round-robin
Slice: 4096
Flags: NONE
GenID: 0
SyncID: 1
ID: 2858761865
Providers:
1. Name: mirror/gm0
Mediasize: 1500301909504 (1.4T)
Sectorsize: 512
Mode: r8w7e8
Consumers:
1. Name: ad10
Mediasize: 1500301910016 (1.4T)
Sectorsize: 512
Mode: r1w1e1
State: ACTIVE
Priority: 0
Flags: DIRTY
GenID: 0
SyncID: 1
ID: 1691608728
2. Name: ad16
Mediasize: 1500301910016 (1.4T)
Sectorsize: 512
Mode: r1w1e1
State: SYNCHRONIZING
Priority: 0
Flags: DIRTY, SYNCHRONIZING
GenID: 0
SyncID: 1
Synchronized: 0%
ID: 1437675374

Synchronization can go on a long time (in my case about 7 hours)

Congratulate! When synchronized obtain 100% you can cut off one of your hdd and try to boot system for checking efficiency of RAID1 massive.

Oh…at last…
If one of your HDDs out of order – replace defective HDD and give command:

howtobsd#gmirror forget gm0
howtobsd#gmirror insert gm0 /dev/ad16