How do I configure a HP DAT Drive for SCO Unix?

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Problem: How do I configure a HP DAT Drive for SCO Unix?

Solution:  To install the relevant driver and device files on an SCO system, perform the following steps:

  1. Run mkdev tape as root.
  2. Select Configure SCSI tape drive.
  3. Select Install tape drive
  4. Select the appropriate SCSI adapter.
  5. Select the appropriate SCSI bus.
  6. Select the Target ID to match the SCSI ID set on the back of the drive.
  7. Select the LUN to be 0.
  8. Enter ‘y‘ to update the SCSI configuration.
  9. Enter the following details:

    Vendor identification string: HP
    SCSI version to which the drive conforms: 2
    Response Data Format (SCSI-2): 2
    DAT device: 4

    Note: If no other device is configured, this procedure will automatically make the tape drive the default device. If another device is already configured, this procedure will make the new tape drive the default device.

  10. Enter’ q’ to leave the boot string displayed when the system is rebooted unchanged.
  11. Enter ‘q’ to return to the Main Menu.
  12. Enter’ q’ to quit.
  13. You are now prompted to rebuild the kernel and the kernel environment (which includes the device files). Perform both steps by answering ‘y’ when prompted, and select the new kernel to be booted by default. 

 You can now use either of the following device files, as appropriate, for backup operations:

  •  If you require a no-rewind device, use: /dev/nrStpY  
  •  If you require a rewind device, use: /dev/rStpY

Where Y is the instance number as assigned to the drive by the operating system (where O is the first device, 1 is the second, etc.).  

For an HP SureStore DAT24x6e autoloader, specify the control device /dev/xStpY through the ‘-d’ option when using mtx.


Controlling Compression with SCO

Because SCO does not have compression/no-compression device files, you must use ‘tape setcomp’ to control the compression status of the drive as follows:  

Command Compression Decompression
tape -a O setcomp disabled disabled
tape -a 1 setcomp enabled disabled
tape -a 2 setcomp disabled enabled
tape -a 3 setcomp enabled enabled

If you have multiple drives, you must specify the appropriate device files in the command, for example:

% tape -a O setcomp /dev/nrStp2

Use tape getcomp to tell you the current status of the drive. 

Note: Do not use the SCO ‘mt’ utility . This is obsolete and does not perform the same function as ‘mt’ on other platforms. Use ‘tape‘ to achieve the same result.


Improving Performance Through Block Size on SCO

To improve performance on a SCO system, you can specify larger blocking factors for cpio and tar. Use tar with the ‘b‘ option and an argument of 20 or cpio with the ‘B‘ option. For example:

%  tar cvbf  20 /dev/rStpY ./*  


% find / -print | cpio -ocB > Idev/rStpY

 or, if you have a version of SCO UNIX earlier than 5.x:  

% find / -print | cpio -ocB -O/dev/rStpY

Where y is the instance number assigned to the drive by the operating system (where 0 is the first device, 1 is the second, etc.).

Alternatively, you can use the tape command as follows:

 % tape -a 32768 setblk <device file>

This explicitly sets the block size used for the drive When you are using built-in applications such as cpio and tar. The <device file> is either /dev/nrStpX or /dev/rStpX, as described above.

Testing Newly Installed Tape Drive

To test perform the following steps.  First you will archive to the tape the /tmp directory and then restore the /tmp directory into /tmp/tmp.

  1. cd /tmp
  2. tar -cvf /dev/rStp0 ./* (note the rStp0 is for the 1st tape drive, if it was the 2nd it would be /dev/rStp1 etc…)
    You should see the archiving occurring since the –v (verbose) argument was used.
  3. If all the files in the /tmp directory were archived perform the restore.
    From within the /tmp directory enter:
    mkdir /tmp/tmp
    cd /tmp/tmp

    tar -xvf /dev/rStp0
    You should now see all the files being extracted into the /tmp/tmp subdirectory.
  4. cd /tmp/tmp and verify all the files in /tmp are also in /tmp/tmp.



Note:  If installing on a Compaq Server see article: “Notice Data underrun” message appears when I use a Compaq 32-bit Fast SCSI-2 host adapter.  You may perform the steps in article in this article after re-linking the kernel for the tape drive to prevent the error message from appearing at all.

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