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This remote-assistance capabi lity allows for assignment of
the proper level of aid to a problem at the earliest possible
moment and permits customer self-help in increasing system
availability.
ERROR LOGGING
RBM provides hardware error detection and the automatic
logging of such errors to a special file. This error-log file
then serves as a history of errors that may be analyzed and
listed by an on-line program (in chronological or sorted
order) for use by customer or Xerox maintenance personnel.
Query of the error log reveals the quantity and type of
errors, frequency of occurrence, and the distribution of
device status reported at time of error. Analysis of error-
frequency changes and other factors leads to schedu ling of
maintenance prior to actual failure, and lessens the time
required for analysis and correction of unpredicted fai lures.
Sites that use this feature provide Xerox with an error-log
database to be examined during scheduled or unscheduled
maintenance.
Whether the system special ist is using
Remote Assistance or is actually at the site, he takes
advantage of the error log summary, sorted listing, and
chronological listing to maintain the system and increase
its avai labi I ity.
The user's operations personnel can also
benefit by the error-log summary by using it to monitor
their system's performance over a period of time.
SYSERR ANALYSIS
RBM provides the capability to obtain a formatted represen-
tation of the internal state of system tables and contents of
memory. The displayed data is segregated and labeled as
to significance. This provides the local or remote Xerox
system specialist (or the user) with a simplified means of
seeing and understanding abnormal system states without
having to decipher a raw hexadecimal dump. It is espe-
cially useful in reducing the time required to isolate prob-
lems that can be detected by their effect upon system-table
data.
The format of output is optimized for display on line
printers, but may be displayed on other devices. In fact,
the Remote Assistance system specialist expects to analyze
such displays at his console, as one of his most valuable re-
mote problem-solving tools.
2
Avai labi I ity Features
DEVICE ISOlATION
Noncritical devices
th~t
are known to be faulty or considered
to be marginal can be isolated from the system by operator
control. Whi Ie the device is being exercised, repaired, or
replaced, RBM continues to operate any programs that do
not mandatorily and specifically require that particular de-
vice.
Thus, in many cases the system is now sti I I avai lable
when formerly it wou Id have been "down". The on-I ine de-
vice exerciser tests (described below) may be run only on
devices that have been so isolated (i.e., made unavai lable
to normal access).
RBM allows device-address substitution between devices of
the same model number (except for disk devices).
This
permits, for example, switching (by means of an operator
key-in) from one magnetic tape drive to another of the same
type.
ON-LINE DEVICE EXERCISERS
Prior to exercise, a device is isolated from normal system
use, via the local or remote-assistance console.
Then the
device exercisers (to the exclusion of any other programs)
operate the device, verifying its functional capabi I ity and
recording any errors in the error log. Upon completion of
such a device test, a device status message is printed at the
operator's console to indicate whether or not the device is
capable of operating within normal service requirements. If
so, the device becomes eligible for return to the system. A
device that fails to pass these tests should be scheduled for
maintenance.
The exercisers are not designed to diagnose the device at
the component level.
Rather, they exercise the device's
functional capabilities in the user environment (without
interfering with the operation of RBM with respect to its
other functions).
Recoverable errors are seen by examina-
tion of the error log, while irrecoverable errors cause the
exerciser to report that the device did not pass the testing.
One appropriate use of the on-line device exercisers is to
check the assumed operational reliability of a device that
has just undergone maintenance or repair, prior to returning
it to normal service.
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