Tape Drive Densities and Special Files

Contents

About this document
    Related documentation
Densities and tapes
How to change the density settings
Using the rmtX.Y special files
An example
Media supplies
Cleaning recommendations
Warranty information

About this document

This document addresses some common questions about tape drives, densities, and rmtX.Y special files. This document is applicable to AIX Versions 3.2 and 4.1.

Related documentation

For detailed information concerning all supported tape drives, see Chapter 10 of the System Management Guide, SC23-2457.

This document is a small subset of the document called "Tape Help" which is provided by Austin RS/6000 Brand I/O Product Engineering at the following URL:

http://www.rs6000.ibm.com/support/micro/tapewhdr.html

Densities and tapes

Due to the vast amount of information and the changes which come about from each new tape product, this information is no longer directly maintained by the Sysback/Tape Drive support group. This information is maintained by Austin RS/6000 Brand I/O Product Engineering at the following URL:

http://www.rs6000.ibm.com/support/micro/tapewhdr.html

This site is maintained and updated regularly. It contains tape interchange and density information for currently supported products. The information below is historical data which is no longer maintained at this site.

9348 Model 012 9-Track

Density Setting             Description
2                   Writes in 1600 bits per inch
3                   Writes in 6250 bits per inch

How to change the density settings

For a listing of possible values for the density settings for various tape drives, see the information in the "Densities and tapes" section of this document.

  1. At the command line, type the following: 
       smit tape
  2. Select Change/Show Characteristics of a Tape Drive.
  3. Look for the name of your tape drive.
  4. If you see the name of the tape drive, determine its rmt numeric identifier and select it.
  5. If you do not see the name of your drive, look for the selection Other SCSI Tape Drive, determine its rmt identifier, then select it.
  6. At the bottom of the menu, you will see: 
       DENSITY setting #1  {  } 
   DENSITY setting #2  {  }

    To select a writing density, type in the number which corresponds to the desired density for the tape drive model you have.
    NOTES:

    1. Do not type in the QIC number or gigabyte number. Enter instead the corresponding density setting number. See the section "Densities and tapes" in this document.
    2. Do not use leading zeros (0). 015 is not the same as 15.

Using the rmtX.Y special files

You can predefine two writing-density settings which you can later choose by specifying the Y extension of the rmtX.Y special file. If you do not define the settings, the default settings for the tape drive will be used.

The following charts in the lefthand column show possible values for the density settings with various tape drives. The charts in the righthand column show the tapes that can be used with the drives.

The rmtX.Y file is used in commands, such as backup, to specify the tape drive device. For example, 

   backup -0 -u / /dev/rmt0

The X part of the rmtX.Y file name specifies which tape drive is used. The first tape drive connected is rmt0, the second is rmt1, and so on. The Y extension on the file name specifies the tape drive action and writing density as shown in the following chart: 

Special File      Retension    Rewind    Density Setting
rmtX              no           yes       1
rmtX.1            no           no        1 
rmtX.2            yes          yes       1
rmtX.3            yes          no        1
rmtX.4            no           yes       2
rmtX.5            no           no        2
rmtX.6            yes          yes       2
rmtX.7            yes          no        2

An example

Suppose you have a 7207 1/4" tape drive and you have set Density #1 = 16 and Density #2 = 15.

If you use special file rmt0.3, the drive will write in QIC 150 density, will not rewind, and will retension.

If you use special file rmt0.6, the drive will write in QIC 120 density, rewind, and retension.

Media supplies

Purchase supplies and accessories from IBM's authorized distributors.

Cleaning recommendations

Warranty information

If you use unsupported media, including unsupported cleaning media, you will void your warranty. Video grade tapes are NOT supported.


[ Doc Ref: 90605224314668     Publish Date: Nov. 14, 2000     4FAX Ref: 1896 ]