This is caused when you have removed a previously mounted T3 volume and created a new one of a different size.

For instance, before removing the T3 volume named "sizetest", format looks like this:

    
Part      Tag    Flag     Cylinders        Size            Blocks
  0       root    wm       0 -    63      128.00MB    (64/0/0)       262144
  1       swap    wu      64 -   127      128.00MB    (64/0/0)       262144
  2     backup    wu       0 - 34144       66.69GB    (34145/0/0) 139857920
  3 unassigned    wm       0                0         (0/0/0)             0
  4 unassigned    wm       0                0         (0/0/0)             0
  5 unassigned    wm       0                0         (0/0/0)             0
  6        usr    wm     128 - 34144       66.44GB    (34017/0/0) 139333632
  7 unassigned    wm       0                0         (0/0/0)             0      

The vol list output looks like this:

volume        capacity   raid   data     standby
      
sizetest       71.6 GB    0     u2d1-4    none 
         

Remove the volume "sizetest" by running

stor-t300-d:/:<9>vol unmount sizetest
stor-t300-d:/:<9>vol remove sizetest

Create a new volume called "sizetest", but make it a different size.  Make sure to initialize it and mount it. 

(Duplicated when "vol init fast" is used...)

Now, vol list shows this:

volume        capacity   raid   data     standby
      
sizetest      143.2 GB    0     u2d1-8    none 
         

In format, do partition>print and the output will look the same as before:

Part      Tag    Flag     Cylinders         Size            Blocks
  0      root     wm       0 -    63      128.00MB    (64/0/0)       262144
  1       swap    wu      64 -   127      128.00MB    (64/0/0)       262144
  2     backup    wu       0 - 34144       66.69GB    (34145/0/0) 139857920

  3 unassigned    wm       0                0         (0/0/0)             0
  4 unassigned    wm       0                0         (0/0/0)             0
  5 unassigned    wm       0                0         (0/0/0)             0
  6        usr    wm     128 - 34144       66.44GB    (34017/0/0) 139333632
  7 unassigned    wm       0                0         (0/0/0)             0
       

This is where the problem is now seen by the customer because the customer is expecting to see a size of 133.38gb in format, but only sees 66.44gb.

The way to fix this is to run format, choose the device and then the "type" option.  You will see something like this:

AVAILABLE DRIVE TYPES:
        0. Auto configure
        1. Quantum ProDrive 80S
        2. Quantum ProDrive 105S
        3. CDC Wren IV 94171-344
        4. SUN0104
        5. SUN0207
        6. SUN0327
        7. SUN0340
        8. SUN0424
        9. SUN0535
        10. SUN0669
        11. SUN1.0G
        12. SUN1.05
        13. SUN1.3G
        14. SUN2.1G
        15. SUN2.9G
        16. Zip 100
        17. Zip 250
        18. SUN9.0G
        19. SUN-T300-0116
        20. SUN-T300-0116
        21. other
Specify disk type (enter its number)[20]:

Choose "Auto configure" and you will see an output like this:

c2t2d1: configured with capacity of 133.38 GB
<SUN-T300-0116 cyl 34145 alt 2 hd 32 sec 128>
selecting c2t2d1
[disk formatted]

Next, label the disk and then do "partition>print" and you will now see the correct size in format:
 

Part      Tag    Flag     Cylinders         Size           Blocks 
  0       root    wm       0 -    31      128.00MB    (32/0/0)       262144
  1       swap    wu      32 -    63      128.00MB    (32/0/0)       262144
  2     backup    wu       0 - 34144      133.38GB    (34145/0/0) 279715840
  3 unassigned    wm       0                0         (0/0/0)             0
  4 unassigned    wm       0                0         (0/0/0)             0
  5 unassigned    wm       0                0         (0/0/0)             0
  6        usr    wm      64 - 34144      133.13GB    (34081/0/0) 279191552
  7 unassigned    wm       0                0         (0/0/0)             0      

NOTE: This procedure is detailed in the "Sun StorEge T300 Administrator's Guide" in section 3.4, "Volume Labeling".