Using Firewire To Access Tape Drives

Whether you are using x86 or PPC Linux, the IEEE1394, or Firewire, interface provides an alternative connection for tape drives to either IDE or SCSI. In fact, there are adapters available from companies like 2nd Wave, Microtech, and Ratoc Systems that provide interface conversion allowing the use of almost any SCSI tape devices on your Firewire port.

To utilize these devices, whether native 1394 like the VXA from Exabyte, or via the 1394 to SCSI converters, requires the proper configuration of the Linux kernel. The necessary drivers are the ieee1394.o, ohci1394.o, and sbp2.o. These drivers are generally available as modules in the more popular distributions. To determine their status on your system, examine the contents of the


/lib/modules/KERNEL_VERSION/kernel/drivers/ieee1394
 

directory on your system. For example, under Yellow Dog Linux 2.3, the kernel version is 2.2.22 or 2.4.19-4a, depending upon which kernel you've installed. Under Red Hat 7.3, the default kernel is 2.4.18-3 (which is a bad kernel for tape, BTW).

If the modules are there, your task is nearly complete - insmod the drivers and start using the drive:

insmod ieee1394
insmod ohci1394
insmod sbp2

If the modules installed properly, you will be able to access the tape drive as /dev/st0 or /dev/nst0 using the standard tape utilities - mt, tar, cpio, dd, and others.

I Don't Have The IEEE1394 Modules

In this case, you will need to rebuild your kernel's device driver modules. Check in /usr/src and make sure that you have the kernel sources installed. If not, you will need to retrieve them from your distribution CD's or from kernel.org or one of its mirrors.

Next, run the config tool of your choosing (please review the Linux Kernel HOWTO as kernel configuration is FAR beyond the scope of this document). You will need to enable "Prompt for development and/or incomplete code/drivers" under the "Code maturity level options" section for the IEEE1394 options to be accessible.

Select <M>odule for the top level IEEE 1394 support. This will allow you to select the other options. Next, set OHCI-1394 support and SBP-2 support to <M>.

The other options are not required, so you may ignore them or include them as you wish.

Finally, execute the appropriate build steps to build and install the new IEEE1394 driver modules and follow the insmod instructions above.

That's it! You may now access the tape drive as if it were a sttandard SCSI tape device via the /dev/st0 and /dev/nst0 device nodes. Also, if you execute 'cat /proc/scsi/scsi', you will see your tape drive listed in the SCSI devices list.