IBM System/370 145 Manual page 195

SECTION 50: RELIABILITY. AVAILAB][LITY, AND SERVICEABILITY (RAS)
FEATURES
50:05 INTRODUCTION
With the growth of more and more online data processing activities,
as distinguished from traditional batch accounting functions, the
availability of a data processing system becomes a very essential factor
in company operations, and
complet~e
system failure is extremely
disruptive. Because of the growirllg frequency of online processing and
the fact that the Model 145 is des:igned to operate in such an
environment, IBM has provided all €!xtensi ve group of advanced
reliabili ty, availability, and se:r:'viceabili ty features for the
System/370 Model 145. These RAS f:eatures are designed to improve the
reliability of system hardware, to increase the availability of the
computing system, and to improve
t~he
serviceability of system hardware
components.
The objective of the RAS featu:r:'es of the System/310 Model 145 is to
reduce the frequency and impact of' system interrupti ons that are caused
by hardware failure and necessitate a re-IPL. RAS features are as
follows:
• Hardware reliability is enhanced through use of more reliable
components.
• Recovery facilities, both hardware and program supported, not
available for System/360 Models 30 and 40, are provided to reduce
the number of failures that cause a complete system termination.
This permits deferred maintenance.
• Repair procedures include more online diagnosis and repair of
malfunctions concurrent with normal job execution in
a
multiprogrammdng environment in order to reduce the effect of such
repairs on system unavailable time.
Each RAS feature, recovery or repair, is discussed in the remainder
of this section.
The following recovery features are implemented in hardware:
• Retry of failing CPU operations
• Eec
validity checking on processor and control storage to correct
all single-bit and detect all double-bit errors
• I/O operation retry facilities, including channel retry data
provided in the limited channe.l logout area, and channel/control
unit command retry procedures to correct failing
I/O
operations
• Expanded machine check interruption facilities to facilitate better
error reco,rding and recovery p:r:ocedures
The following recovery features are provided by programming systems:
• Recovery management support
(~~S)
to handle the expanded machine
check interruption and channel retry data. MCH and CCH routines are
provided for OS (except for PCP). MCAR and CCH routines are
provided for DOS versions.
A Guide to the IBM System/310 Mode:L 145 185