This example shows you how to use tape automation to perform backups across a network. IBM manufactures several automated tape libraries (ATLs) that you can attach to your system to provide tape automation. An automated tape library is both a resource to the system and a device. A tape library contains one or more tape drives. ATL models available from IBM are:
You can share any of the IBM tape libraries across multiple systems. However, due to drive connectivity limitations, you cannot attach individual drives to more than two systems at once unless these are attached using a Fiber Channel. ATLs with more than two drives (3575 and 3494) can attach to more than two systems. When i5/OS uses a tape library, it allocates a drive resource to the job. If a library has more than one drive, i5/OS selects one or more depending on the type of save operation (serial, concurrent or parallel). If a resource is unavailable, i5/OS queues the request until one becomes available or until the device timeout period elapses. You can find more information about how to use devices in Chapter 8 of this manual. You can find more information about ATLs in Automated Tape Library Planning and Management book (SC41-5309).
In this example, assume the use of a 3494 ATL with two 3590 devices shared between two systems. You have connected the two tape drives to two systems, SYSTEMA and SYSTEMB. These two systems exist in a BRMS network, and share a common tape pool. When working with tape libraries, you should have the stand-alone device description varied off, and the library device varied on. The tape drives appear as resources under the library device. With a 3494, although each tape subsystem appears to the i5/OS as a library device, all library devices can access the resources for that library type. The i5/OS command Work with Media Library Status (WRKMLBSTS) display illustrates this.
Work with Media Library Status
System: RCHAS400
Type options, press Enter.
1=Vary on 2=Vary off 3=Reset resource 4=Allocate resource
5=Allocate unprotected 6=Deallocate resource 8=Work with description
Device/ Job
Opt Resource Status Allocation name
TAPMLB01 VARIED ON
TAP01 OPERATIONAL UNPROTECTED
TAP02 OPERATIONAL UNPROTECTED
TAPMLB02 VARIED OFF
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Parameters or command
===>
F3=Exit F4=Prompt F5=Refresh F9=Retrieve F12=Cancel F17=Position to
F23=More options
This example shows the preferred way to run, which is with one library device varied on and the other varied off. This way, both SYSTEMA and SYSTEMB can run jobs simultaneously. Both would be using library device TAPMLB01. Although only two tape resources (TAP01 and TAP02) are available, each system can run more than two jobs at the same time. The i5/OS resource manager queues requests for resources by allocating them as needed and as they become available. To use one of the resources specifically (as you might in a more complex library setup), you can change the allocation of the non-required resource to DEALLOCATED. This makes the resource unavailable to that system. You can also change the resource allocation manually by using the WRKMLBSTS display. However, if you want to change the allocation dynamically, type the VRYCFG command in an *EXIT command in your control group. For example, if we want i5/OS to select TAPMLB02 to save the PAYROLL application, we could create the following control group items:
Edit Backup Control Group Entries RCHAS400
Group . . . . . . . . . . : SAMPLE
Default activity . . . . . *BKUPCY
Text . . . . . . . . . . . Create sample backup control group
Type information, press Enter.
Auxiliary Weekly Retain Save SWA
Backup List Storage Activity Object While Message
Seq Items Type Pool Device SMTWTFS Detail Active Queue
10 *EXIT *DFTACT
20 PAYDATA *SYSBAS *DFTACT *ERR *NO
30 PAYLIB *SYSBAS *DFTACT *ERR *NO
40 *EXIT *DFTACT
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F3=Exit F5=Refresh F10=Change item F11=Display exits
F12=Cancel F14=Display client omit status F24=More keys
Code the *EXIT at sequence number 10 as follows:
User Exit Maintenance KITKAT
Type command, press Enter.
Sequence number . . . . . . . : 10
Where used . . . . . . . . . : *EXIT
Weekly activity . . . . . . . : *DFTACT SMTWTFS
Command . . . . . . . . . . . . VRYCFG CFGOBJ(TAPMLB01) STATUS(*DEALLOCATE)
RSRCNAME(TAP02) CFGTYPE(*MLBRSC)
...
F3=Exit F4=Prompt F12=Cancel
Code the *EXIT at sequence number 40 as follows:
User Exit Maintenance KITKAT
Type command, press Enter.
Sequence number . . . . . . . : 40
Where used . . . . . . . . . : *EXIT
Weekly activity . . . . . . . : *DFTACT SMTWTFS
Command . . . . . . . . . . . . VRYCFG CFGOBJ(TAPMLB01) CFGTYPE(*MLBRSC) STA
TUS(*UNPROTECTED) RSRCNAME(TAP02)
...
F3=Exit F4=Prompt F12=Cancel