TECH TIP FOR HP SYSTEMS

TZ88x and SWXTL-Cx Loaders And Sequential Mode

In certain operations, after a loader ejects a tape cartridge from a drive and 
places it in it's repository slot, the cartridge in the next sequential slot 
will be automatically moved into the tape drive. (This is the default behavior 
of the TZ88 family of tape drives.) Some applications, such as HP's OmniBack II 
and Legato's NetWorker, will produce errors when they independently attempt to 
place a tape into a drive since one will be there already. The dltseq_op utility 
can correct this problem by changing mode page parameters within the tape drives 
from sequential mode to random mode. 

Description of the dltseq_op utility

The dltseq_op utility is used to change the DISLDRAUTOLDMC parameter of the 
Vendor Unique Mode Page (3Eh) from the default 0 to a value of 1. This allows 
the loader to operate in a random access mode instead of the default sequential 
mode. With a value set to 1 (random access mode enabled), after a tape is 
returned to it's repository slot, no other tapes will be automatically moved to 
the tape drive.  

Utility usage: 

     Load a tape into the tape drive. 
     If you type... 

     dltseq_op

     ...and press the enter key, command usage information is displayed as follows:

          Usage: ./dltseq_op -s|-r [-v] device
                 -s specifies sequential operation
                 -r specifies random operation
                 -v specifies verbose output

     For example, if you type... 

     dltseq_op -r /dev/rmt/c1t5d0BEST

     ...and press the enter key, you will execute the utility specifying random 
     operation to device /dev/rmtc1t5dBEST. 

Use whatever the pathname is to the tape drive unit, not the loader robotics 
character device file. It the example above, /dev/rmt/c1t5d0BEST is the path to 
the tape drive unit.

If you also specify the -v command line option, the Vendor Unique Mode Page 
(3Eh) values will be output. You can do this to view the DISLDRAUTOLDMC 
parameter and to verify that it is set to a 1 value. 

Execution with the tape2 driver 

     To execute this utility on a server using the tape2 driver, reboot the 
kernel you used to change the device product id string when you ran the TZ882DLT 
utility, or create a new kernel using the instructions provided with the 
TZ882DLT utility. Insert a DLT cartridge tape into the drive, execute the 
dltseq_op utility, and use the -v command line option to make sure that the 
DISLDRAUTOLDMC bit changed from 0 to 1. Now reboot your running (normal) kernel 
and the loader will be in random access mode.   Execution with the stape driver 

     On systems using the stape driver, simply execute the utility. No special 
kernel modifications should be necessary. The stape driver should be attached to 
the device at LUN 0. Run the dltseq_op utility, and the loader will be in random 
mode. You will be using this kernel for normal operation. 

Troubleshooting 

If the following error occurs when you are using the tape2 driver and a tape is 
loaded into the drive, the spt driver has not been attached to LUN 0 of the 
loader. 

 # ./dltseq_op -r -v /dev/rmt/0m
 -r
 -v
 /dev/rmt/0m
  SIOC_IO inquiry ioctl: Invalid argument

If the following error occurs, a tape is probably not loaded into the drive. Or, 
if you are using the tape2 driver, the spt driver has not been attached to LUN 0 
of the loader. 

 # ./dltseq_op.uu -r -v /dev/rmt/0m
 -r
 -v
 /dev/rmt/0m
 open: I/O error
