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Appendix E. Remote-linked Libraries 627
1st ed., 6/30/04 - 312579601
Programming and Operational Considerations
The following are programming and operational considerations that should be observed if
you have libraries resembling any of the illustrated configurations. The HSC permits
operation of these library configurations provided that some programming and operational
precautions are observed.
These precautions are based on various functional restrictions described in following
paragraphs. Table 80 lists the functions and the programming precautions that must be
followed for associated configurations.
Resolving CDS Issues After a Remote-Link Failure
In configurations 3, 4, and 5, if there is a failure in the remote link while ACS1 has a
hardware reserve issued against the primary CDS, ACS0 is locked out and is not able to
perform any automated tape services until the reserve is released. This problem can
happen even if the two ACSs are not remote-linked.
The reserve can be released by disabling the remote-link interface. Operator intervention
is required to disable the link.
Restore Involving Journals from Channel-Extended Hosts
In configurations 3, 4, and 5, if a restore of the control data set is needed, and the
journaling option is invoked, all journal files must be obtained from every host that was
included in the library LIBGEN. If all of the journals are not applied when the RESTore
utility is executed, an accurate control data set may not be constructed during the restore
operation.
Obtaining all journals from remote-linked hosts can be a problem if the link is down.
Consequently, not all journals can be obtained to fully satisfy a successful restore of the
control data set.
Careful planning must be done before executing the RESTore utility to ensure that
journals are available from each host and that the remote link is fully operational when the
restore operation is performed.
Control Data Set Integrity
In configurations 3, 4, and 5, the primary control data set and the secondary control data
set are separated across a remote link. If the link is interrupted, the secondary data set
becomes the primary control data set for ACS1.
Table 80. Programming and Operation Precautions for Remote-linked Libraries
Function Applicable Configuration(s)
Resolving CDS issues after a remote-link failure 3 - 5
Restore involving journals from channel extended
hosts
3 - 5
Control data set integrity 3 - 5