I/O Error Recording and SVC 76 V8/370 maintains an error recording area that caFtures I/O, CCH, and BCB error records. Device and control unit detected unit checks during V8/370 spooling, paging, and virtual machine I/O errors generate the I/O records. V8/370 and the virtual machine's LOGREC data set contain recorded I/O errors; this double recording occurs when the virtual machine's
operating system does not invoke SVC 76.
If the virtual machine operating system invokes SVC 76 and passes the
correct parameters to V8/310, V8/370 records the error in its own error
recording area. VM/370 then passes control back to the virtual machine operating system, thus bypassing virtual machine error recording
facilities. VM/370 Recovery Features
The V!/370 recovery features are described more fully in the VBL11Q and RECORDING FACILITIES
The OS/VS Environmental Recording, Editing, and printing program (EREP) is executed when the CMS CPEREP command is invoked. The output of the CPEREP command consists of printed reports whose content depends upon
the specified (or defaulted) CPEREP operands and upon the input system error records. The reports generated by CPEREP have the salle format as
those generated on an OS/VS system. The input system error records aay be froa the V8/370 error recording area or fre. a history tape. The
history tape may have been produced earlier by CPEREP froa the V8/370 error recording area data or by an OS/VS system from SYS1.LOGREC data. Unlabeled tapes produced on OS/VS systems by OS/VS EREP and on V!/370 systeas by CPEREP are compatible and can be transported between systeas.
Data froll both systems can also be accumulated on the same tape,. For aore details on CPEREP, refer to the following publications: VBL11Q gnd l!!Q! and the f!inting If the facilities of an IB! 3850 Mass Storage System (!SS) are used
with VM/370 virtual machine operations and !SS errors are reflected to V8/370's error recording area, CPEREP aust be invoked so that 8SS-related errors recorded in the error recording area can be collected
on an accumulation (ACC=YES) tape for further processing by the VS System Data Analyzer Program (SDA). Because ess logged-out data is
voluminous and the interrelationships of !SS components are complex, it
is imperative that this service program be used to effectively diagnose
and isolate mass storage problems. 4 V8/370 Operator's Guide

VM/370 Repair Facilities The Online Test Standalone Executive Program (OLTSEP) and associated Online Tests (OLT) execute in a virtual machine that can run
concurrently with normal system operations. These programs provide
online diagnosis of I/O errors for most devices that connect to the System/370. The service representative (with a CP command privilege class of F)
can execute online tests from a terminal as a user of the system; CP console functions, including the ability to display or alter virtual
machine storage, are available when these tests are run. Those tests
that violate V8/370 restrictions may not run correctly in a virtual
machine environment. VM/370 Restart Facilities Whenever a system failure causes an abnormal termination of the real machine that does not result in a disabled WAIT state, V8/370 attempts
to reload CP. Often, the operator needs to take no action. The system
attempts to execute a warm start, thus allowing user's terminals to be
reconnected (for logon reinitialization by users) and completed spool
files as well as open console spool files to be maintained. In the
event of a warm start, device reconfiguration (such as varying a device
offline) that was performed by the real computing system operator is remembered by CP for system spooling devices only. Storage
reconfiguration data acquired during the process of reccvering from real
storage errors is lost. After a V8/370 system failure, each user must
re-access V!/370 (LOGON), and each virtual machine must be reloaded (IPLed) • Termination of a virtual machine, whether caused by a real computing system malfunction or a virtual machine program error, normally does not
affect the execution of other virtual machines unless the error involves
shared segments.
In V8/370 attached processor operations, the priorities and restart
activities are similar to a uniprocessor mode of operation. However# if system damage assessment indicates a nonrecoverable operation on the
attached processor and the error can be isolated to a virtual aachine, V5/370 will be continued in uniprocessor mode on the main processor.
All virtual machines with an AFFINITY setting are automatically reset to AFFINITY OFF for subsequent virtual machine processing. (Note, the
affected virtual machines are placed in console function mode.) If a
virtual machine was running when the malfunction occurred, its operation
will be terminated.
Note: See the VARY PROCESSOR command in "Section 3. CP Commands" for
Instructions on hoW to vary the attached processcr back online.
If a similar malfunction occurred on the main processor while V8/370 was operating in attached processor mode, V5/370 terminates. V8/370 cannot switch to uniprocessor operation on the attached processor unit
because the attached processor unit has no hardware interface for
input/output capabilities. Section 1. Intro. to Operational Ctrl. of the V8/370 System 5