Examples--Displaying Tape Drive Status

The following example shows the status for a QIC-150 tape drive (/dev/rmt/0):

$ mt -f /dev/rmt/0 status
Archive QIC-150 tape drive:
   sense key(0x0)= No Additional Sense   residual= 0   retries= 0
   file no= 0   block no= 0

The following example shows the status for an Exabyte tape drive (/dev/rmt/1):

$ mt -f /dev/rmt/1 status
Exabyte EXB-8200 8mm tape drive:
sense key(0x0)= NO Additional Sense residual= 0  retries= 0
file no= 0   block no= 0

The following example shows a quick way to poll a system and locate all of its tape drives:

$ for drive in 0 1 2 3 4 5 6 7
> do
> mt -f /dev/rmt/$drive status
> done
Archive QIC-150 tape drive:
   sense key(0x0)= No Additional Sense   residual= 0   retries= 0
   file no= 0   block no= 0
/dev/rmt/1: No such file or directory
/dev/rmt/2: No such file or directory
/dev/rmt/3: No such file or directory
/dev/rmt/4: No such file or directory
/dev/rmt/5: No such file or directory
/dev/rmt/6: No such file or directory
/dev/rmt/7: No such file or directory
$ 

Handling Magnetic Tape Cartridges

If errors occur when a tape is being read, you can retension the tape, clean the tape drive, and then try again.

How to Retension a Magnetic Tape Cartridge

Retension a magnetic tape cartridge with the mt command.

For example:

$ mt -f /dev/rmt/1 retension
$

Note - Do not retension non-QIC tape drives.

How to Rewind a Magnetic Tape Cartridge

To rewind a magnetic tape cartridge, use the mt command.

For example:

$ mt -f /dev/rmt/1 rewind
$

Guidelines for Drive Maintenance and Media Handling

A backup tape that cannot be read is useless. So, periodically clean and check your tape drives to ensure correct operation. See your hardware manuals for instructions on procedures for cleaning a tape drive. You can check your tape hardware by doing either of the following:

• Copying some files to the tape, reading the files back, and then comparing the original files with the copied files.

• Using the -v option of the ufsdump command to verify the contents of the media with the source file system. The file system must be unmounted or completely idle for the -v option to be effective.

Be aware that hardware can fail in ways that the system does not report.

Always label your tapes after a backup. If you are using a backup strategy similar to the strategies suggested in Chapter 46, Backing Up and Restoring File Systems (Overview), you should indicate on the label "Tape A," "Tape B," and so forth. This label should never change. Every time you do a backup, make another tape label that contains the following information:

• The backup date

• The name of the machine and file system backed up

• The backup level

• The tape number (1 of n, if the backup spans multiple volumes)

• Any information specific to your site

Store your tapes in a dust-free safe location, away from magnetic equipment. Some sites store archived tapes in fireproof cabinets at remote locations.

You should create and maintain a log that tracks which media (tape volume) stores each job (backup) and the location of each backed-up file.