Zone cloning with zfs

Sun documentation about zone cloning describe if zone cloning, which zonepath is on a ZFS pool, zone will be cloning by zfs snapshot. On my system zones cloned by files copying. How I can troubleshoot that?

root@sunhost # cat /etc/release 
                       Solaris 10 10/09 s10x_u8wos_08a X86 
           Copyright 2009 Sun Microsystems, Inc.  All Rights Reserved. 
                        Use is subject to license terms. 
                           Assembled 16 September 2009 
root@sunhost # zoneadm list -vc 
  ID NAME             STATUS     PATH                           BRAND    IP 
   0 global           running    /                              native   shared 
   - template         installed  /zones/template                native   shared 
root@sunhost # zfs list 
NAME                     USED  AVAIL  REFER  MOUNTPOINT 
rpool                   18.1G   181G    34K  /rpool 
rpool/ROOT              10.1G   181G    21K  legacy 
rpool/ROOT/s10x_u8      10.1G   181G  4.47G  / 
rpool/ROOT/s10x_u8/var  5.62G   181G  5.62G  /var 
rpool/dump              1.00G   181G  1.00G  - 
rpool/export            50.5K   181G    23K  /export 
rpool/export/home       27.5K   181G  27.5K  /export/home 
rpool/swap                 4G   185G    16K  - 
rpool/template          3.03G   181G  3.03G  /zones/template 
root@sunhost # zonecfg -z twiki -f /tmp/template 
root@sunhost # zonecfg -z twiki verify 
root@sunhost # time zoneadm -z twiki clone template 
Copying /zones/template... 

real    11m57.221s 
user    0m4.420s 
sys     0m56.695s 
root@sunhost # zfs list 
NAME                     USED  AVAIL  REFER  MOUNTPOINT 
rpool                   22.8G   176G    34K  /rpool 
rpool/ROOT              14.8G   176G    21K  legacy 
rpool/ROOT/s10x_u8      14.8G   176G  9.13G  / 
rpool/ROOT/s10x_u8/var  5.62G   176G  5.62G  /var 
rpool/dump              1.00G   176G  1.00G  - 
rpool/export            50.5K   176G    23K  /export 
rpool/export/home       27.5K   176G  27.5K  /export/home 
rpool/swap                 4G   180G    16K  - 
rpool/template          3.03G   176G  3.03G  /zones/template 
root@sunhost # zoneadm list -vc 
  ID NAME             STATUS     PATH                           BRAND    IP 
   0 global           running    /                              native   shared 
   - template         installed  /zones/template                native   shared 
   - twiki            installed  /zones/twiki                   native   shared

PS. sorry for my english.