Scsi Tape and Solaris/X86

I have used a Seagate CTT8000 4G tape backup unit with Solaris X86, even though it is not on the compatibility list.

Configuring the tape device

Become root; add this line to the /kernel/drv/st.conf file:

"CONNER   CTT8000-S",	"Seagate 4G Dat",	"DAT"

(note the three spaces after the word "CONNER"). If you have a different scsi tape device, then note the Scsi ID string (you can do this on a system with an Adaptec Scsi controller by rebooting, and typing ^A during the boot; select Scsi Utilities, and it will display a list of Scsi devices. The last item assumes that you have a standard DAT drive; if not, you need to make a new entry in the st.conf file for that type of drive; see "man st" for details. You will need to know hardware details such as block length, etc.

Then execute these commands:

# touch /reconfigure
# reboot

For more details, see "SCSI Tape Drives" in the X86 Device Configuration Guide.

Using the Drive

You can use the tape tool; it is a GUI front end to using tar. Note that you can add a directory as well as a file to the "File to write" list, and then it will recurse into that directory. I prefer not to use this, as you can't see the list of files as it is working.

You can also use tar to read or write to the tape unit, using these commands:

For a table of contents of the tape:
tar tv > files.lst

To create a new backup:
tar cvX exclude.tar /

To update the backup (perform an incremental backup):
tar uvX exclude.tar /

To restore everything:
tar xv

To restore one file or directory:
tar xv //path/file_or_dir
Note the use of the double slash, since all files are "relative to /". Even after the the required file(s) is/are found, tar will continue searching the whole tape, which may take about 30 minutes. You can interrupt it safely by typing ^C.

Become superuser so you don't have problems with access.

The file exclude.tar should contain a list of files or directories that should not be backed up; this should include "/dev" (otherwise, the backup will hang on /dev/fd, at least). Mine has this content:

//dev
//cdrom
//floppy
//devices
//proc
//tmp

Make sure that there are no blank lines or spaces in this file. If you use the tape tool, make sure you specify the exclude file (press the Props... button, then the Exclude button). Also remember to log in as root before running OpenWindows.

When trying the backup for the first time, it might be worth putting the major first level directories (/usr, /var, /opt, and /export) into the exclude file, so that there is a small number of directories left, and you can make sure that everything is working, and you have all the special directories excluded.

SCSI tape device file names

If the tape drive refuses to work, and says something like

tar: /dev/rmt/0: no such device or address

you could try

tar tvf /dev/rmt/1

and vary the last file name; ls to see all possible options. I somewhere found that the first digit is the scsi address, second letter is sometimes "c" for compression, and "b" means berkeley behaviour. I can't find out the source of this information.

If say "1cb" is the default you want to use, you can save some typing by editing the first line in /etc/default/tar to be the one you want. That way you don't have to include the -f 1cb in all tar commands. If using the tape tool, you can set the device in one of the option screens.