When I try to format a slice in Solaris 10 I get the follow error :

-bash-3.00# mkfs /dev/dsk/c1d0s5 18877824
Can not determine partition size: Inappropriate ioctl for device


Some format command output:....

AVAILABLE DISK SELECTIONS:
0. c1d0 <DEFAULT cyl 38735 alt 2 hd 64 sec 63>
/pci@0,0/pci-ide@7/ide@0/cmdk@0,0
1. c2d0 <DEFAULT cyl 39887 alt 2 hd 64 sec 63>
/pci@0,0/pci-ide@7/ide@1/cmdk@0,0


partition> p
Current partition table (original):
Total disk cylinders available: 38735 + 2 (reserved cylinders)

Part Tag Flag Cylinders Size Blocks
0 root wm 6227 - 21464 29.30GB (15238/0/0)
61439616
1 swap wu 3 - 1018 1.95GB (1016/0/0)
4096512
2 backup wm 0 - 38734 74.47GB (38735/0/0)
156179520
3 unassigned wm 6118 - 6168 100.41MB (51/0/0)
205632
4 unassigned wm 6168 - 6218 100.41MB (51/0/0)
205632
5 unassigned wm 1070 - 5751 9.00GB (4682/0/0)
18877824
6 unassigned wm 21465 - 38734 33.20GB (17270/0/0)
69632640
7 unassigned wm 0 0 (0/0/0)
0
8 boot wu 0 - 0 1.97MB (1/0/0)
4032
9 alternates wu 1 - 2 3.94MB (2/0/0)
8064


If I try to mount that slice I got:

-bash-3.00# mount /dev/dsk/c1d0s5 /mnt/tmp/
mount: /dev/dsk/c1d0s5 is not this fstype

What's wrong? Can you help me ?

Thanks

Fabio