DFSMStvs could encounter the following categories of problems,
shown in ascending order of impact on the user:
- Those problems within the system logger that the system logger
resolves for itself.
DFSMStvs has no involvement in this category
and the problem might be perceived as merely an increase in response
times.
There is also a dependency on RRS. If RRS encounters
a problem, perhaps with one of its log streams, DFSMStvs is impacted.
If RRS is not active or fails, DFSMStvs is impacted.
- The system logger is unable to immediately satisfy a DFSMStvs
request. This problem state can be encountered on a structure full
condition where the coupling facility has reached its capacity before
offloading data to DASD. This state can also be encountered during
the rebuilding of a coupling facility structure.
DFSMStvs is able
to recognize this situation and retries the request every three seconds
until the request is satisfied. Typically, this can take up to a minute.
Message IGW838I is issued to indicate that this has occurred.
- If the system logger fails, DFSMStvs becomes disabled. If the
system log has not been damaged, a subsequent restart of DFSMStvs
should succeed.
- If a return code implies that the system log has
been damaged or records have been lost, DFSMStvs is quiesced. This
means that transactions run to completion as far as possible with
no further records written to the system log. You must then specify
TV_START_TYPE(COLD) in your IGDSMSxx member of SYS1.PARMLIB
and use the SET SMS command to cold start DFSMStvs.
Recommendation: After
a cold start, data sets for which recovery was not completed could
be left in a damaged state and must be recovered manually. If the
data sets are forward recoverable, their forward recovery logs might
also be damaged. Manually recover the data sets (without using forward
recovery), take backups of them and of any other data sets that use
the same forward recovery log, and then delete and redefine the forward
recovery log.
If a return code implies damage to
a forward recovery log or one of the system logs, DFSMStvs quiesces
the log, and the units of recovery run to completion. The data needed
to back out in-flight units of recovery is lost, and some manual recovery
might be necessary.
Before you continue to use the
log stream, follow these steps:
- Delete and redefine the log stream.
- Take an image copy of all data sets that reference the log stream.
- Unquiesce the affected logs.
- In some circumstances, DFSMStvs quiesces a data set. You must
unquiesce it. Then you can explicitly open the data set.
DFSMStvs does not provide any mechanism to automatically
delete records from forward recovery log streams. You must delete
such data in order to manage the size of forward recovery log streams.
If you need long-term data retention of data in the log stream, you
might want to copy the data from log stream storage to alternative
archive storage.