Lost root password - Solaris 10

Hi,

We have a M4000 server with 2 internal disks that 1 of them installed Solaris 11 and the other installed Solaris 10.

We have problem in logging in the Solaris 10 for root ID due to password issue.

We booted the server into Solaris 11 and tried to mount the disk that with Solaris 10 but with the following message:

# mount /dev/dsk/c1t1d0s0 /a                                     

mount: /dev/dsk/c1t1d0s0 is not this fstype

The following information is from the OK prompt:

{1} ok printenv boot-device   

boot-device =           /pci@0,600000/pci@0/pci@8/pci@0/scsi@1/disk@0,0:a /pci@0,600000/pci@0/pci@8/pci@0/scsi@1/disk@1,0:a

Appreciate any advise how to go about it. Thanks in advance.