zfsbsd# uname -rs
FreeBSD 7.2-STABLE

Lets take a look at our zfs-root setup.

zfsbsd# zpool status
  pool: rpool
 state: ONLINE
 scrub: none requested
config:

	NAME        STATE     READ WRITE CKSUM
	rpool       ONLINE       0     0     0
	  ad0p3     ONLINE       0     0     0

errors: No known data errors

zfsbsd# zfs list -t all
NAME                     USED  AVAIL  REFER  MOUNTPOINT
rpool/ROOT               252M  6.89G    20K  /rpool/ROOT
rpool/ROOT/oldBE         252M  6.89G   252M  /rpool/ROOT/oldBE
rpool/ROOT/oldBE@oldBE   287K      -   252M  -
rpool/tmp                 29K  6.89G    29K  /tmp
rpool/usr-local         1.66M  6.89G  1.66M  /usr/local
rpool/var               81.9M  6.89G  81.9M  /var

Our current boot-environment is called "oldBE" and is mounted on /.

zfsbsd# manageBE list
Poolname: rpool
BE    Active Active Mountpoint        Space
Name  Now    Reboot -                 Used 
----  ------ ------ ----------        -----
oldBE yes    yes    /rpool/ROOT/oldBE  252M

zfsbsd# mount
rpool/ROOT/oldBE on / (zfs, local)
devfs on /dev (devfs, local)
rpool on /rpool (zfs, local)
rpool/ROOT on /rpool/ROOT (zfs, local)
rpool/tmp on /tmp (zfs, local)
rpool/usr-local on /usr/local (zfs, local)
rpool/var on /var (zfs, local)

Lets create a new boot-environment "newBE" using the old boot-environment "oldBE" as source, thus including all the files.

zfsbsd# manageBE create 
Usage: manageBE create -n <newBE> -s <sourceBE> -p <pool>

zfsbsd# manageBE create -n newBE -s oldBE -p rpool
Install new kernel with option 'DESTDIR=/rpool/ROOT/newBE/' and run 'manageBE activate -n newBE -p rpool'

The new boot-environment was created, it is not yet activated but mounted on "/rpool/ROOT/newBE/"

zfsbsd# manageBE list
Poolname: rpool
BE    Active Active Mountpoint        Space
Name  Now    Reboot -                 Used 
----  ------ ------ ----------        -----
newBE no     no     /rpool/ROOT/newBE     0
oldBE yes    yes    /rpool/ROOT/oldBE  252M

zfsbsd# mount
rpool/ROOT/oldBE on / (zfs, local)
devfs on /dev (devfs, local)
rpool on /rpool (zfs, local)
rpool/ROOT on /rpool/ROOT (zfs, local)
rpool/ROOT/newBE on /rpool/ROOT/newBE (zfs, local)
rpool/tmp on /tmp (zfs, local)
rpool/usr-local on /usr/local (zfs, local)
rpool/var on /var (zfs, local)

Now you could do a "freebsd-update -b /rpool/ROOT/newBE" or "make installkernel DESTDIR=/rpool/ROOT/newBE/".

After that, we activate the new boot-environment too boot from it.

zfsbsd# manageBE activate -n newBE -p rpool

We can see that it is activated on the next reboot.

zfsbsd# manageBE list
Poolname: rpool
BE    Active Active Mountpoint        Space
Name  Now    Reboot -                 Used 
----  ------ ------ ----------        -----
newBE no     yes    /rpool/ROOT/newBE  252M
oldBE yes    no     /rpool/ROOT/oldBE  252M

Lets fire it up!

zfsbsd# reboot

After the reboot.

zfsbsd# uname -rs
FreeBSD 7.2-STABLE

Now the new boot-environment is enable and in use, the old is mounted but not in use anymore.

zfsbsd# manageBE list
Poolname: rpool
BE    Active Active Mountpoint        Space
Name  Now    Reboot -                 Used 
----  ------ ------ ----------        -----
newBE yes    yes    /rpool/ROOT/newBE  253M
oldBE no     no     /rpool/ROOT/oldBE  383K

zfsbsd# mount
rpool/ROOT/newBE on / (zfs, local)
rpool/ROOT on /rpool/ROOT (zfs, local)
rpool/ROOT/oldBE on /rpool/ROOT/oldBE (zfs, local)
rpool/tmp on /tmp (zfs, local)
rpool/usr-local on /usr/local (zfs, local)
rpool/var on /var (zfs, local)

zfsbsd# zfs list -t all
NAME                     USED  AVAIL  REFER  MOUNTPOINT
rpool/ROOT               253M  6.89G    21K  /rpool/ROOT
rpool/ROOT/newBE         253M  6.89G   252M  /rpool/ROOT/newBE
rpool/ROOT/newBE@oldBE   391K      -   252M  -
rpool/ROOT/newBE@newBE   185K      -   252M  -
rpool/ROOT/oldBE         383K  6.89G   252M  /rpool/ROOT/oldBE
rpool/tmp                 29K  6.89G    29K  /tmp
rpool/usr-local         1.66M  6.89G  1.66M  /usr/local
rpool/var               81.9M  6.89G  81.9M  /var

Lets get rid of the old boot-environment if we don't need it anymore.

zfsbsd# manageBE delete
Usage: manageBE delete -n <BE> -p <pool> -o [yes|no]

The -o option deletes the snapshot the old boot-environment is depending on too.

zfsbsd# manageBE delete -n oldBE -p rpool -o yes

Yep its gone.

zfsbsd# zfs list -t all
NAME                     USED  AVAIL  REFER  MOUNTPOINT
rpool/ROOT               253M  6.89G    19K  /rpool/ROOT
rpool/ROOT/newBE         253M  6.89G   252M  /rpool/ROOT/newBE
rpool/ROOT/newBE@oldBE   706K      -   252M  -
rpool/tmp                 29K  6.89G    29K  /tmp
rpool/usr-local         1.66M  6.89G  1.66M  /usr/local
rpool/var               81.9M  6.89G  81.9M  /var

zfsbsd# manageBE list
Poolname: rpool
BE    Active Active Mountpoint        Space
Name  Now    Reboot -                 Used 
----  ------ ------ ----------        -----
newBE yes    yes    /rpool/ROOT/newBE  253M

zfsbsd# mount
rpool/ROOT/newBE on / (zfs, local)
devfs on /dev (devfs, local)
rpool on /rpool (zfs, local)
rpool/ROOT on /rpool/ROOT (zfs, local)
rpool/tmp on /tmp (zfs, local)
rpool/usr-local on /usr/local (zfs, local)
rpool/var on /var (zfs, local)