How to check Hard disk problem at ok prompt in solaris

How to check Hard disk problem at ok prompt in solaris

The command i tried
ok devalias
screen                   /pci@1f,2000/TSI,gfxp@1
net                      /pci@1f,4000/network@1,1
disk                     /pci@1f,4000/scsi@3/disk@0,0
cdrom                    /pci@1f,4000/scsi@3/disk@6,0:f
tape                     /pci@1f,4000/scsi@3,1/tape@4,0
tape1                    /pci@1f,4000/scsi@3,1/tape@5,0
tape0                    /pci@1f,4000/scsi@3,1/tape@4,0
disk6                    /pci@1f,4000/scsi@3/disk@6,0
disk5                    /pci@1f,4000/scsi@3/disk@5,0
disk4                    /pci@1f,4000/scsi@3/disk@4,0
disk3                    /pci@1f,4000/scsi@3/disk@3,0
disk2                    /pci@1f,4000/scsi@3/disk@2,0
disk1                    /pci@1f,4000/scsi@3/disk@1,0
disk0                    /pci@1f,4000/scsi@3/disk@0,0
scsi              

ok probe-scsi-all
/pci@1f,4000/scsi@3,1

/pci@1f,4000/scsi@3
Target 1
  Unit 0   Disk     SEAGATE ST318404LSUN18G 5221
Target 6
  Unit 0   Removable Read Only device    TOSHIBA XM6201TASUN32XCD1103