You can update certain attributes of a DASD-only or coupling facility log stream using either the IXGINVNT UPDATE service or the IXCMIAPU utility. The updates are immediately reflected in the log stream definition in the LOGR couple data set, but some remain pending and do not take effect until specific events occur during processing as described in this section.
The RETPD and AUTODELETE attributes can be modified regardless of whether there are any active connections to the log stream. The updates remain pending until the next data set switch event or the subsequent first connection to the log stream in a sysplex.
The following attributes can be updated while there is an outstanding
connection to the log stream. Some of the updates will not
take effect immediately if there is an outstanding connection. In
order to update these attributes, the LOGR couple data set must be
formatted at z/OS® Release 2 or higher. See LOGR parameters for format utility in z/OS MVS Setting Up a Sysplex for
more details.
Note: This requirement does not apply to the LOWOFFLOAD,
HIGHOFFLOAD, and OFFLOADRECALL attributes. For all others, if this
requirement is not met, the UPDATE request fails.
Pending
updates will take effect at different points for each log stream attribute
as follows:- The LS_DATACLASS, LS_SIZE, LS_MGMTCLASS, and LS_STORCLASS attribute updates will remain pending until a new offload data set is allocated (data set switch event) or the subsequent first connection to the log stream. For a coupling facility log stream, the update also takes effect during the next structure rebuild (user-managed or system-managed).
- The LOWOFFLOAD, HIGHOFFLOAD, OFFLOADRECALL, STG_DATACLAS, STG_MGMTCLAS,
STG_STORCLAS, STG_SIZE,
and WARNPRIMARY
attribute
updates remain pending until the subsequent first connection to the
log stream in the sysplex. For a coupling facility log stream,
the update also takes effect during the next structure rebuild (user-managed
or system-managed). - The LOGGERDUPLEX, STG_DUPLEX, and DUPLEXMODE attribute updates remain pending until the subsequent first connection to the log stream in a sysplex or until the next successful structure rebuild (user-managed).
- The MAXBUFSIZE attribute update remains pending until the subsequent first connection to the DASD-only log stream in the sysplex.
- The ZAI and ZAIDATA attributes can be updated while there is an
outstanding connection to the log stream. In this case, the change
will immediately be reflected in the log stream definition. The updated
specification will take effect on the following logger events for
this log stream:
- On the subsequent first connection to the log stream on a system (z/OS image).
- As a result of a SETLOGR FORCE,ZAICONN,LSN= command on the target system. or
- As a result of a SETLOGR FORCE,ZAICONN,ALL command when there is a connection to this log stream currently using the ZAI=YES setting on the target system.
Note: Since the updated value can be used on a system by system basis, the installation should ensure the proper actions are taken on all the systems with connections to the log stream in order to make use of the current value.
You can also rename a log stream dynamically using the NEWSTREAMNAME keyword on
the IXGINVNT REQUEST=UPDATE request. You can rename a log stream
dynamically. Since many logging programs use a fixed log stream
name, this function can be very useful for log stream recovery. For
example, if a log stream fails the system may not be able to perform
any logging for the log stream that has failed. Using the log stream
rename function, you can rename the failing log stream, and then use
the IXGINVNT REQUEST=DEFINE to define a new log stream with the old
name in order to start logging again. This function allows you to:
- Save the current data in a renamed log stream and get logging started quickly by defining a new log stream with the expected name.
- Let existing services/utilities access the data in the renamed log stream to reduce the effect of having some data missing from the log stream.
- Perform problem diagnosis, such as data missing conditions, on the original (renamed) log stream resources at the same time that new work continues.