To limit the number of times a specific request can be retried.
To reject EJECT requests from vaults that reside in (or are part of) an automated tape library.
To confirm (allow) EJECT requests only if they are from the Control-M/Tape Active library (MAINLIB). (For a sample exit that performs this function, see the CTTX008W member in the IOA SAMPEXIT library.)
To reject retry requests when the previous action failed with a specific return code and/or reason code. For example, Exit 8 may confirm retry requests only if the previous failure was not a permanent one.
Sites With More Than One Type of Automated Tape Library
Control-M/Tape can interface with a maximum of four different types of automated tape libraries.
At a site with more than one library, automated tape library action requests are sent to each automated tape library until the request is satisfied.
Exit 8 is called separately before each automated tape library is accessed. The exit can be used to reject commands for volser ranges that are not relevant to the automated tape library, thereby saving valuable processing time. For example, if all the volumes with a given volser prefix are stored in an IBM automated tape library, Exit 8 can be used to suppress actions for volsers with this prefix when requested from a StorageTek library.
Note: SMS-managed automated tape library from different vendors are considered as one library (meaning, Exit 8 is called only once for all SMS-managed automated tape libraries.
Sites With No IOA Functional Monitor Installed
As mentioned earlier in this chapter, the IOA Functional monitor is used both to pass requests for automated tape library actions from Control-M/Tape online screens, and to retry previously failed requests.
If the IOA Functional monitor is not installed at your site, and you do not intend to implement it, Exit 8 can be used to reject requests from the Online environment and retry requests from all the environments, thereby saving valuable space in the Trace file (that is used to store these requests until the monitor processes them).
It is recommended that you disallow retry requests at sites that do not use an IOA Functional monitor. To do this, edit sample Exit 8 in the CTTX008R member in the IOA SAMPEXIT library, and specify that 0 retries should be allowed.
Note: This sample exit can also be used at sites using an IOA Functional monitor to limit the number of retries to any desired number.
