IBM FlashSystem 900, Service Manual

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Service Processor MAPs
3746-900 Concurrent Maintenance
The 3746-900 allows concurrent maintenance.
Concurrent maintenance lets you isolate a
resource from a system while the system is oper-
ating, without impacting the operations of the other
resources. After the resource has been isolated
from the rest of the system, it can be tested and
replaced if necessary. When the problem is cor-
rected the resource is given back to the system.
Concurrent maintenance is initiated by the oper-
ator and has two aspects: concurrent diagnostics
and concurrent repair.
Concurrent Diagnostics
Product characteristics which allow you to run
concurrent diagnostics are as follow:
¹
The distributed structure of the processors
and couplers with the capability of a selective
re-IML or selective resource.
¹
The service bus circulating from the CBSA to
the processors, and the CS which allows you
to collect test results.
Concurrent Repair
Concurrent repair is made possible by the hot-
pluggable capability of 3746-900 FRUs:
processors, couplers, and the SPS. The hot-
pluggability is made possible by the following
characteristics:
¹
The cassette pins are of variable length; the
longer pins being used for the ground.
¹
The vendor technology logic (VTL) layer as a
protection between the CMOS-2 and the
external signals.
¹
The ability of the 'coupler presence' signal to
de-gate the bus drivers on the processor and
to control the coupler power via the processor
microcode.
¹
In addition, the state of any 3746-900
resource reflected in the CDF-E includes the
'present' or 'not present' state. When the
resource is present the status 'available' or
'unavailable' is given. The resource is set to
not available when it is in concurrent mainte-
nance.
Concurrent Mode Activation
Procedure
The procedure to put a processor in 'concurrent'
mode for maintenance is given here as an
example. A similar procedure applies for the other
FRUs:
¹
The lines controlled by the processor are
deactivated from the host.
¹
From the service processor, the 'concurrent'
mode is entered for the processor. The moni-
toring of the processor via the 'sanity frames'
is stopped. At the same time, the processor
is checked for no active lines (a processor is
only accepted in 'concurrent' if no lines are
active).
When a processor is set to 'concurrent' mode,
all the associated underlying resources
(example: couplers) are also set to 'concur-
rent' mode, except if the processor has a
backup (since the backup processor continues
to work with these resources).
¹
Unplug the cassette processor.
The processor- presence monitoring task in
the CBSP detects that the processor is
unplugged and an alarm is displayed on the
service processor console.
¹
Plug the new processor in.
The processor-presence monitoring task in
CBSP detects the processor being plugged in.
The processor VPDs are read and an alarm is
displayed. The processor state in the CDF-E
is set to 'concurrent' mode.
¹
According to the type of processor, the diag-
nostics for that processor must be run.
¹
The resource is initialized (IMLed).
¹
From the service processor console, the
command, quit 'concurrent' mode,is given for
the processor.
¹
The lines are reactivated from the host.
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3746-900: Service Guide