We were using an IBM 3580 LTO-4 unit with SLES11 sp1 and used tar with a -b option of 16384 to speed up the transfer of 400Gb to tape.
For access to the drive we had the IBM lin-tape driver installed.
After upgrading to SLES11 SP2 the -b option of tar is maximized to 2048. All higher values give an error
The speed of the transfer to tape is acceptable but we can't read our old tapes.
We did install the latest lin_tape driver
Does anyone know where the maximum block-size of a SCSI attached tape unit is determined.