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When a channel or an I/O device error occurs on a Model 165, the
appropriate ERP is scheduled to perform recovery procedures.
If the
error is corrected, operations continue normally.
If the error cannot
be corrected (it is permanent), error recording occurs (see OBR/SDR
discussion below).
If I/O RMS or a user-written permanent error-
handling routine is not present, the affected OS task is abnormally
terminated.
The operator is notified of permanent I/O errors.
ERP
routines written for the 3330 and 2305 facilities and the 3211 Printer
will include support of the larger number of sense bytes provided by
the control units of these devices.
STATISTICAL DATA RECORDER (SDR) AND OUTBOARD RECORDER (OBR)
OBR and SDR routines are included in alIOS control programs.
These
routines are requested by the ERP routines during their processing.
The SDR routine is requested when one of the error statistics counters
becomes full.
Counters are maintained in the resident control program
storage area for each I/O device in the system configuration.
SDR
records these statistics in the appropriate SDR summary record for
that device contained in the error log data set SYS1.LOGREC.
This
insures recording of temporary I/O device error data.
The OBR routine
records both temporary and permanent channel errors and writes an
outboard record containing pertinent status data whenever a permanent
error occurs for a device.
SDR is also executed when a permanent error
occurs to write accumulated statistics for that device.
ENVIRONMENT RECORDING, EDIT, AND PRINT PROGRAM (EREP)
OS EREP is a standard system utility that can be initiated as a
job step via standard job control statements at any time.
It contains
model-dependent routines and will be extended to handle all the status
records written by OS RMS routines for System/370.
It performs the
following:
1.
Edits and prints all error records contained in SYS1.LOGREC.
These records have been constructed and written by MCH, CCH,
OBR. and SDR routines.
2.
Accumulates a history of specified record types from SYS1.LOGREC
by creating or updating an accumulation data set
3.
Edits and prints a summary of selected records from SYS1.LOGREC
or an accumulation data set
I/O RMS (APR AND DDR)
I/O RMS routines are optional, model-independent routines supported
for MFT and MVT environments.
These reconfiguration procedures attempt
to minimize the number of abnormal job terminations and unscheduled
system halts that occur because of errors on channels or I/O devices.
The alternate path retry (APR) routine provides for the retry of
a failing I/O
ope~ation
on another channel path to the device involved,
if one is available, when an uncorrectable channel error occurs.
Thus
APR, if present, is entered from a device-dependent ERP when a permanent
error is deemed to exist after retry procedures have been attempted.
If the I/O error is corrected by a retry using the alternate channel
path, operations continue.
If a permanent error still exists, the
task is abnormally terminated unless the DDR routine is present.
A
malfunctioning channel path can be varied offline by the operator if
necessary.
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