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Chapter 2. Host Software Component Functions 51
1st ed., 6/30/04 - 312579601
that are not directly affected. Then, these subsystems can be recycled (brought down and
then restarted) to pick up the changed information. Cycling the affected HSCs can be done
at a convenient time, with only one HSC down at a time. This permits an HSC server to
remain up, servicing requests from clients.
Note: In many instances, the SET utility can run while HSC subsystem(s) are active.
However, some SET options require that the HSC(s) affected must be down, e.g.,
SET HOSTID.
In most cases, the LSM and/or ACS affected must remain offline until HSCs on
affected hosts are recycled, e.g., when deleting or changing drive unit addresses with
SET SLIDRIVS.
In most cases, all affected HSCs must be recycled to reinitialize and support the new
configuration. Refer to “SET Utility” on page 392 for restrictions on the specific
SET options and processes to follow when making configuration changes.
Defining a New Configuration to Avoid Future Reconfigurations
When you define a new configuration with LIBGEN, you can add some flexibility to
avoid running reconfigurations in the future.
• If additional hosts may be added later, define dummy host IDs now.
Entries for future hosts can be defined in the SLILIBRY macro,
HOSTID=(host0,...,host15) parameter. For example, host IDs of FREE1, FREE2,
and FREE3 could be defined. Then, the SET utility HOSTID option can be used to
change these ‘‘reserved’’ host IDs to the new ones being added to the configuration.
• When a CDS is created, it is desirable to allocate more then the minimum amount of
space. The free blocks can be used later when additional drives are added.
Defining Planned ACSs with no Stations
The HSC allows users to define an ACS without specifying station addresses (refer to the
SLIACS macro in the HSC Configuration Guide).
Using this feature means that a planned ACS can be placed into the LIBGEN/SLICREAT
process and remain disconnected without generating message SLS1664A (
‘‘ACS AA is
disconnected’’
) or requiring the user to enter the OPTion DISCmsg command to
suppress SLS1664A.
If planned ACSs have been defined previously with dummy station addresses, these
stations can be removed using the SET SLISTATN utility. In this case, the user does not
specify any output stations. Refer to “SET LMU Station Address Numbers” on page 408
for more details.
When the planned ACS becomes available, SET SLISTATN can be used to add stations
for the ACS. The ACS can then be brought online without recycling the HSC.
SET HOSTID(newhost),FORHOST(FREE1)