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2 - Set Up

Virtual tape support on IBM System i™ started with OS/400 release 5.4. You may find some detail documentation on IBM Redboook   "i5/OS V5R4 Virtual Tape: A Guide to Planning and Implementation". May we recommend that you read at least Chapter 1, Introduction to virtual tape.

Basically, to define a virtual tape you have to go through three steps:

  1. define an image catalog simulating to be set of tape volumes on the Integrated File System
  2. define a virtual tape device
  3. load the virtual tape device with the image catalog.

1-Define an image catalog

As per the mentioned Redbook, a number of system commands are used to define virtual tapes, please refer to Chapter 3, Implementing virtual tape storage.
VRTSAV provides its own commands to make this setup easier.

Command vrtsav/WRKIMG

Figure 2a
Figure 2a - Command WRKIMG

Enter 1 for the option and, for example, SAVSYS for the name of the image catalog to be created, then press Enter.
Figure 2b
Figure 2b - Creating an image catalog

You receive the prompt of command vrtsav/ADDIMG:
Figure 2c
Figure 2c - Command ADDIMG

Through this command you are going to define the size, the number and the names of the virtual tape reels that will contain your saves. This command will generate images of your virtual tape reels in an IFS directory created automatically and named /images/tape/SAVSYS.
These images will have the same name you assign to the volumes, and their sizes will be dynamic, that is they will be inflated while a save is performed.
  • For the volume size, enter the the capacity in megabyte of a tape reel of yours, for instance 400,000.
  • For the volume prefix, enter 3 letters, for instance VOL.
  • Enter the number of volumes that you estimate needed to contain your saves, for instance 1. Should the number of volumes result not enough to contain a save, the system would automatically generate new ones with prefix GEN.
Figure 2d
Figure 2d - Input to command ADDIMG

The IFS image catalog is generated, and you receive the screen in Figure 2e.
Figure 2e
Figure 2e - Image catalog generated

2-Define a virtual tape

Command vrtsav/WRKVRTTAP
Press F22 from the screen in Figure 2e to run command vrtsav/WRKVRTAPP:
Figure 2f
Figure 2f - Command WRKVRTAPP

Enter 1 for the option and, for example, TAPVRT01 for the name of the virtual tape to be created, then press Enter.
Figure 2g
Figure 2g - Creating a virtual tape

You receive the prompt of command vrtsav/CRTVRTTAP:
Figure 2h
Figure 2h - Command vrtsav/CRTVRTTAP

Add some text description and press Enter to receive the prompt of system command CRTDEVTAP (press the Enter key again to display all parameters):
Figure 2i
Figure 2i - System command CRTDEVTAP

Press the Enter key to run command CRTDEVTAP. You receive the following screen:
Figure 2j
Figure 2j - Virtual tape created

3-Load the virtual tape device with the image catalog

Select the virtual tape with option 22 to display the available image catalogs:
Figure 2k
Figure 2k - Select the image catalog to be connected
(see Note 1 at the end of this page)

Select with a 1 the image catalog to be connected (loaded into the virtual tape). You receive the following screen:
Figure 2l
Figure 2l - Image catalog now connected to the virtual tape

Press F3 to exit from WRKVRTTAP and to return to the WRKIMG screen:
Figure 2m
Figure 2m - WRKIMG screen when virtual tape connected

Press F3 again to exit from the WRKIMG screen.

NOTE 1 - After selecting the catalog image to be connected to the virtual tape, you may receive an error message (MCH5204) saying the resource VRTTAPnn is not available, thus causing the image catalog fail to be loaded into the virtual tape.
In such a case, do the following:

  1. go back to the screen in figure 2j and delete the failing virtual device
  2. follow the procedure from figure 2f on, to re-create the same virtual tape device,
  3. however, when you come to the screen in Figure 2i (system command CRTDEVTAP), in parameter Resource name, instead of leaving *VRT, enter a specific resource name, VRTTAPnn, where nn is a value in the range 01-35.

NOTE 2 - In this page we have documented a set up process that starts with command vrtsav/WRKIMG and goes through command vrtsav/WRKVRTTAP.
A setup process can also proceed the opposite way, starting with command vrtsav/WRKVRTTAP and completing with command vrtsav/WRKIMG.

NOTE 3 - You may use the setup technique documented in this page to set up several virtual tape drives. Up to 35 virtual tape drives can be defined.
You can use a virtual tape drive in the same way as you would use a real tape drive, the only difference being that its tape reels are replaced by image catalog volumes.
For instance you can save individual libraries on virtual tapes and perform restore operations from them.
You can copy (command DUPTAP) the virtual tapes to real tape volumes and store them safely, and you can copy real tape volumes to virtual tapes, for instance to perform restore operations.

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