z/OS MVS Setting Up a Sysplex
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When unrecoverable DASD I/O errors occur during offload

z/OS MVS Setting Up a Sysplex
SA23-1399-00

DASD I/O errors may occur during offload processing, while log data is being written to DASD log data sets. When this happens, system logger tries to recover by closing the current log data set and allocating a new one. If this process fails, the I/O error is characterized as an unrecoverable I/O error.

In the case of unrecoverable I/O errors, system logger will accept subsequent IXGWRITE requests as follows:
  • For a coupling facility log stream, system logger will accept IXGWRITE requests if the log stream is connected to a coupling facility where there is still room for log data. If the coupling facility is full or no coupling facility exists, system logger rejects IXGWRITE requests.
  • For a DASD-only log stream, system logger will accept IXGWRITE requests until the staging data set for the system writing to the log stream is filled.

IXGBRWSE and IXGDELET requests may continue to work. I/O errors encountered in the process of completing these requests are reported to the application in return and reason codes.

To correct an unrecoverable I/O problem, delete the log stream definition in the LOGR policy and redefine it with different log data set attributes, such as LS_DATACLAS, in order to get the log stream data set allocated in a usable location.

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