CHAPTER 7: TAPE AND CD MEDIA Utilities
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There are a number of Unix utilities for moving files from tape to disk, disk to tape, disk to disk, and disk to CD media. This section will outline some of the basic uses of these utilities.

This chapter will cover the following information:

• The mt Command
• The tar Command
• The dd Command
• CD Writer

The above device names are generic names.  Depending on your application the actual device name will vary, for instance, to utilize the no rewind option on pinon the device name would be /dev/rmt/tps0d2nr.  For specific information on each architecture, refer to the following man pages about the SCSI drive interfaces.

man tps (SGI)
man tz  (Compaq Alpha)
man st  (Sun)

7.1 The mt Command

        Syntax: mt -f device command count

        mt -f /dev/nrmt0h rewind

        mt -f /dev/nrmt0h fsf 5

        bsf count  Move backward count files. 
        bsr count  Move backward count records.        
        fsr count  Move forward count records.
        eof count  Write count end-of-file marks at 
                   current position on tape.

        status     Get status of tape device.

On-line Information

man mt

7.2 The tar Command

The tape archive utility, tar, saves and restores multiple files to and from a single tape or archive file (tar file). There are various options for creating a tar file and extracting files from it.

        Syntax: tar options device directory

         tar -tv /dev/rmt0h

         tar -tvf file.tar

1.      List the tape's contents to find the top-level 
        directory name as shown above.

2.      Enter the following.

        cd /user1/jones/data 

        mkdir directory

        tar -xv /dev/rmt0h

To write a tar file to tape, use the c (create) option. For instance, user jones can make a tar file of her entire directory with the following command:

        cd /user1/jones

        tar -cv /dev/rmt0h .

        cd /user1/jones/
 
        tar -cvf /disk/jones/files.tar files

which would tar up the sub-directory structure files. To read a tar file from disk, set your default to the directory above the one where you want to restore the files, and enter:

        tar -xvf files.tar 

which would restore the files sub-directory structure.

Note: When moving tar files across the network via ftp, be sure to use binary mode.

On-line Information

man tar

7.3 The dd Command

The dd command copies an input file to an output file. These can be either tape-to-disk or disk-to-disk copies. This command is particularly useful for I/O, as it allows you to read and write arbitrary record sizes.

        Syntax: dd options

        dd if=/dev/nrmt0h of=data conv=block

        ibs             Input block size (512 default).
        obs             Output block size (512 default).
        skip=n          Skip n records before starting
                        to copy. 

        files=n         Skip n files before starting to copy.

        conv=unblock    Convert fixed-length records to variable 
                        length records.

On-Line Information

man mt
man tar
man dd

7.4 CD Writer

• Login to mimosa
• Create an ISO9660 file. This takes about 10 minutes for 500MB.
• Move files and/or directory structure into an area that mimosa can access (i.e. off your home directory or /mmmtmp)
• Change directory to the /mimosa disk

mimosa> cd /mimosa

• Execute program to create the ISO9660 file. In the following example, The difax.iso argument is the name of the file on the /mimosa disk that will be transferred to the CDROM, it is built from files in directories found in the next argument, /mmmtmp/boydw/difax in this example.

mimosa> mkisofs -r -o difax.iso /mmmtmp/boydw/difax

• As process is executing, information will be written to the screen.

mimosa> ls

total 484884
-rw-r--r--   1 boyd     users    496023552 Jul 13 08:12 difax.iso

• Next insert the CDR blank into the lower, Yamaha, drive. CD blanks can be obtained from your administrative staff. To burn the CDR execute the following command. NOTE: This command is run with sudo. To acquire sudo privilege submit an assist request.

As the SCSI device will vary between systems, first issue the following:

mimosa>sudo cdrecord -scanbus

Substitute the appropriate numbers in the dev= option below.

mimosa>sudo cdrecord -eject -v -isosize speed=8 dev=0,3,0 difax.iso

• Respect the privacy of others.
• Think before you type.

• Make sure that the ISO9660 file used to burn the CDR is less than 650mb.
• Never put more than 1000 files in one directory.
• Never try to create a CD from a directory structure more than 8 directories deep.