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Using USB Tape Drives on BRU Server for Linux

Views: 13347
Votes: 2
Posted: 15 Jan, 2009

USB Tape Drives on Linux with BRU Server

Description of Problem:

The TOLIS Group Technical Support team has received several calls concerning the use of USB tape drives on Linux with BRU Server installations.

The error message that is seen upon making the attempt to write to the tape device for backup operations is:

brufilter: [W130] warning - write error on first block: errno = 16, Device or resource busy

There are some already known devices that exhibit this problem on Linux and they are as follows:

  • DDS /DAT 3 USB Tape Drives
  • DDS/DAT 4 USB Tape Drives
  • DAT72 USB Tape Drives
  • DAT160 USB Tape Drives
  • AIT -1 USB Tape Drives

As we learn of more devices we will continue to add them to this list.

Resolution:

This problem is caused from an apparent limitation being set by the Linux kernel for block sizes sent over the USB bus.  By default, BRU Server uses a 128k block size.  However, in customer reports, as well as in-house testing, it has been discovered that setting the block size to a value higher than 64k results in the above error.

To resolve this problem, the BRU Server block size must be set to 64k or lower on your BRU Server Linux installation.  To do this, follow the steps below:

  1. Open the BRU Server Console for Linux.
  2. Click on the "Tools" tab.
  3. From the "Database Option" button, select "Device Configuration."
  4. From the "Device" pull down menu, select the USB tape drive that is experiencing the problem.
  5. By default, the block size for BRU Server is 128k, or 131072 bytes. Change the block size to 65536.  65536 is the value for 64k (1024 x 64 = 65536).
  6. Once that has been changed, click the "Save" button in the bottom right corner of the Console.  You may need to enlarge the Console window for the "Refresh," "Cancel," and "Save" buttons to appear.
    The "Status:" report at the bottom of the window should report "Record saved" after clicking the "Save" button.

No further changes need to be made to fix the above problem.  If you plan on using "bru-server.console" or "bru-server.cmd" to make these changes, the syntax for the command is:

setc -m device <device_name> block_size 65536

You must insert the device name in place of <device_name> in the command above.

If you continue to experience problems with your USB tape device on Linux, please contact TOLIS Group Technical Support.

Note: This issue appears to be caused by a Linux OS limitation, not a drive limitation.  The above drives have been tested on Mac OS X & Windows with success using block sizes up to 1MB on some drives.  In all cases, the drives listed above accepted and worked with 128k and 256k block sizes under Mac OS X and Windows.

Others in this Category
document About BRU Server's Architecture
document How do I control my tape library with the libctl (tm) command on Mac OS X?
document How can I test to see if my tape drive/library is operating properly under Mac OS X?
document How do I control tape devices with tapectl(tm)?
document Moving from Retrospect? Information that you need to know before using BRU
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