After upgrade solaris 8 to 9, the vxfs file system cannot be mounted. It gave
the following error:

vxfs mount: /dev/dsk/c1t5d0s6 is not a vxfs file system

Could some one advice. The vxfs version is 3.3
fstyp shows /dev/dsk/c1t5d0s6 is vxfs
fsck shows "file system is clean - log replay is not required"