Does anyone know where or if you can change the block size for the mt devices?  
Via smit or chdev I can change the rmt devices, but no matter what I set the 
rmt device block size to the mt devices are built with a 1024 block size.

tsmserver:/=>lsattr -El rmt0
block_size     64                 BLOCK size (0=variable length)            True
delay          45                 Set delay after a FAILED command          True
density_set_1  0                  DENSITY setting #1                        True
density_set_2  0                  DENSITY setting #2                        True
extfm          yes                Use EXTENDED file marks                   True
location                          Location Label                            True
lun_id         0x1000000000000    Logical Unit Number ID                    Fals
e
mode           yes                Use DEVICE BUFFERS during writes          True
node_name      0x100000068d02efc0 FC Node Name                              Fals
e
res_support    no                 RESERVE/RELEASE support                   True
ret_error      no                 RETURN error on tape change or reset      True
rwtimeout      144                Set timeout for the READ or WRITE command True
scsi_id        0x110ef            SCSI ID                                   Fals
e
var_block_size 0                  BLOCK SIZE for variable length support    True
ww_name        0x100000068d02efc0 FC World Wide Name                        Fals
e

tsmserver:/=>lsattr -El mt0
FCPORT_ID  0x110ef            FC Port ID                  True
LUNMAP_ID  0x1000000000000    Mapped LUN ID of the device True
PRODUCT_ID DLT7000            Product ID of the device    False
WW_NAME    0x100000068d02efc0 WW Name of the Port         False
block_size 1024               Block Size                  True

Thanks
DW