The operating system upgrade plan fails if an inaccessible slice is included in the /etc/vfstab file.
Workaround:
Remove or comment out the nonaccessible slices from the /etc/vfstab file.
otp-eng-s13:/opt/SUNWotp# grep c0t1d0s6 /etc/vfstab #/dev/dsk/c0t1d0s6 /dev/rdsk/c0t1d0s6 /otp1.1 ufs 3 yes - otp-eng-s13:/opt/SUNWotp#