Control Data Corporation CYBER 170 Series Operator's Manual page 30

Value of rrr
(bits 11-9)
001
010
Description
If it becomes necessary to redeadstart
the system (for example, due to system
malfunction), it is recommended that a
level 3 recovery deadstart be
attempted.
If
level 0 is selected, the
system is reloaded from the deadstart
file. All permanent files, queue files (if
QPROTECT is enabledt), and system
dayfiles are recovered. All central'
memory and PP contents are destroyed
by the memory confidence test.
Indicates a level 1 recovery deadstart
whereby the system, all jobs, and all
active .files are recovered from
checkpoint information on mass
storage. . Permanent files are also
recovered. A level 1 deadstart can be
done only if the DSD command CHECK
POINT SYSTEM (refer to section 3) was
successfully executed immediately prior
to deadstart. Once level 1 recovery
deadstart begins, all central memory
and PP contents are destroyed by the
memory confidence test.
Level 1 recovery deadstart is normally
used to allow maintenance to be
performed and then resume normal
processing.
It
is also useful in system
test situations. Level 1 recovery
deadstart should' never be used to
attempt recovery from a system
malfunction or to preserve queue files.
Indicates a level
2
recovery deadstart
whereby all jobs and active files are
recovered from checkpoint information
on mass storage. However, no attempt
is made to recover the system. Instead,
the system is loaded from the deadstart
file as in level 0 deadstart. In all other
respects, level 2 recovery deadstart is
identical to that described for a level 1
recovery deadstart (refer to preceding
description). Once level 2 recovery
deadstart begins, all central memory
and PP contents are destroyed by the
memory confidence test.
Level 2 recovery deadstart is normally
used in system test situations and is not
recommended for the normal production
environment.
Value of rrr
(bits 11-9)
011
Description
Indicates a level 3 recovery deadstart
whereby all jobs, active files, and the
system, with the exception of the
library directory, are recovered from
central memory tables. A level 3
deadstart is the only level that
preserves the contents of central
memory. If a deadstart level less than
3 is selected early in the deadstart
process, a memory test pattern is
written throughout central memory. In
order to avoid inadvertent destruction
of central memory contents when a
level 3 deadstart was intended, it is
recommended that level' 3 is always
selected on the deadstart panel. If a
deadstart level other than 3 is needed,
you can specify the level by changing
the *P* display. The library directory
is recovered from mass storage.
Permanent files are also recovered. A
CHECK POINT SYSTEM command must
have been issued prior to deadstart to
prevent loss of SYSEDIT (system library
modification) information. Only PP
memory confidence testing occurs
during a level 3 recovery deadstart;
central memory is unaffected.
A level 3 recovery deadstart is normally
performed following an equipment
malfunction (for example, channel or
PP hung), providing central memory and
mass storage remain intact. Unless it
can be determined that central memory
is no longer reliable, a level 3 recovery
should be attempted following a
malfunction. If level 3 recovery fails, a
level 0 deadstart must be performed.
I
NOTE
I
Attempting a level 1 or 2
recovery deadstart after a
level 3 deadstart fails will
not correctly recover
system activity and can
endanger system and
permanent file integrity.
You must perform a level 0
deadstart.
For additional information concerning levels of deadstart,
refer to Preparing for Recovery Deadstart later in this
section.
t Refer to the NOS Installation
H~dbook
for more information on the QPROTECT installation option.
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