I suggest you read this
section and this
wikipedia page.
To put it simple:
ad0 -> First PATA Hard Drive using FreeBSDs 'ad' driver.
ad0s1 -> first primary partition on ad0 -- also known as a 'slice'
ad0s1a -> partition 'a' within the disklabel for ad0s1
and so on.
BSD partitioning scheme is different from Linux or DOS and is fully documented.
The slice/partition notation should probably be reversed but I didn't invent the damn thing :\. One BSD slice is a lot like an Extended DOS Partition but you are not limted to haveing 1 of them and depending on the BSD flavor, 8-16partitons in side them in a manor comparable to logical drives.
Same concept from user point of view.
Unless you want to f*** around with things: /boot, /etc, and possibly /bin must be on the / because /boot is needed for bootstrapping. There is probably no sense in moving /sbin off the / either, the space gains not worth the bother unless your back in 1984.
Typical convention is to create either an a and b partition (/ and swap within the slice) or to create several partitions within one or more slices.
this is my OpenBSD systems layout:
Code:
Terry@vectra-$ df -hl
Filesystem Size Used Avail Capacity Mounted on
/dev/wd0a 147M 30.4M 110M 22% /
/dev/wd0h 393M 938K 372M 0% /home
/dev/wd0d 98.3M 6.0K 93.4M 0% /tmp
/dev/wd0g 6.7G 400M 6.0G 6% /usr
/dev/wd0e 148M 10.6M 130M 8% /var
/dev/wd1a 11.8G 96.0M 11.1G 1% /usr/local
/dev/wd1d 44.3G 12.2G 29.9G 29% /srv
Terry@vectra-$
It functions as a headless file server and without X. The /home partition is small for storing local 'notes' and supported users actual files are stored under /srv/protocol/sharename and mounted over the network on the client system.
(at least modern) BSD systems generally name devices as driver major number [additional information].
i.e. xl0 -> first network interface using 'xl' driver, there is no eth0, eth1, etc -> it's all named by driver.
ad0 -> first pata drive on FreeBSD
da0 -> first scsi/usb drive on FreeBSD
wd0 -> first pata drive on OpenBSD
sd0 -> first sci/usb drive on OpenBSD
etc.
FreeBSDs file system uses soft updates and is gaining journaling support -> soft updates is a different way of filling the same need that journaling does.
Using ext3 under FreeBSD is mounted as ext2 -> and that means mounted without journaling so there is no point in using ext2/ext3 as a FreeBSD system slice.
UFS is better suited for system data.
Use FAT32/EXT2 for data to be shared with other OSes read+write, as ReiserFSv3 and JFS == read only in FreeBSD.