296 Implementing IBM Tape in i5/OS
What virtual tape is
The virtual tape concept is a simulated tape environment within i5/OS. It consists of the
following:
򐂰 Virtual tape drives (up to 35)
򐂰 Virtual tapes (256 maximum per image catalog)
򐂰 One or more image catalogs holding the virtual tapes. These are called
image catalog
entries
.
This virtual environment behaves exactly as though there were real tape drives with real
physical tape volumes. The virtual tape volumes are structured exactly like real tapes, with
headers, tape marks, trailer labels, and so on.
You use virtual tapes exactly as you would real tapes. Commands such as DSPTAP, CHKTAP,
and so on behave in the same manner as they would in real tapes. As a user you should not
notice any difference. You can even flip their write protect switch.
Notice the emphasis on the word “exact”. This is because virtual tapes are
exactly like real
tapes, with only a minor difference: since they are virtual, you should copy the virtual tapes to
real tape volumes and store them safely. Apart from this, no other difference exists.
Positioning the virtual tape
This section discusses the positioning of virtual tape and compares it with other virtual media
services and physical tape.
Other virtual media services
The following virtual media services are available:
򐂰 Virtual optical:
This is available in i5/OS V5R2, i5/OS V5R4, and subsequent releases. With this function,
you can load optical images and use them for installation of software and PTFs.
򐂰 Virtual Tape Server (VTS):
This is currently
not available in i5/OS. This function, which is actually a tape server on
which clients can back up their details, is available on some other platforms (for example,
the IBM z/OS platform).
򐂰 Virtual tape:
This is available in i5/OS V5R4 and subsequent releases, and can be used to back up and
restore data from a virtual tape device.
Supported applications and operating systems
The virtual tape function in i5/OS provides the same functionality as a physical tape. There
are, however, a few exceptions with regard to specific functions. These are discussed in
Chapter 4, “Planning for IBM tape in i5/OS” on page 95.
Virtual tape in i5/OS acts as a Random Access Cartridge Loader (RACL), which is still a tape
device and not a media library. All the save commands in i5/OS can use the virtual tape
function.

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