QFS does not support dynamic LUN sizing

Here is the scenario:

We have a QFS shared sam file system using 3 luns running Solaris 10 and QFS 5.2 as below:
1 x 2TB
1 x 2TB
1 x 1.5TB
The file system mounted from the above luns is 5.5TB
We extended the 3rd lun (1.5TB) to 2TB from storage side (3PAR)

The host sees it as 2TB, we updated the QFS config and tried to run growfs


format output:
32. c5t50002AC0000E1477d0 <3pardata -vv-3111-2.00tb="-vv-3111-2.00tb">  601
          /scsi_vhci/ssd@g50002ac0000e1477
33. c5t50002AC0000F1477d0 <3pardata -vv-3111-2.00tb="-vv-3111-2.00tb">  602
          /scsi_vhci/ssd@g50002ac0000f1477
34. c5t50002AC0001A1477d0 <3pardata -vv-3111-2.00tb="-vv-3111-2.00tb">  603   <-- changed from 1.5TB to 2TB
          /scsi_vhci/ssd@g50002ac0001a1477

umount fs
samd config
samgrowfs
mount fs

The file system is still 5.5TB

Unfortunately only thing we can do here is :
backup the file system, samfsdump  
recreate the file system, sammkfs -S

restore the file system again, samfsrestore