Fujitsu Siemens Computers SX series User Manual page 294

Functional scope, concepts and applications
Redundant connection of the BS2000 devices on both system boards:
The XSB may not contain the only or last path to a device – in particular the home
pubset must be taken into account here – which cannot be placed in the DETACHED
state.
This condition is satisfied in the case of a redundant hardware connection and by the
use of PowerPath (see also the "PowerPath" manual [34]).
Situation-dependent requirements
When it is started, BS2000/VM2000 has control over whether a DR process is initiated and,
if the process is a DR-disconnect which affects the resources of BS2000/VM2000, control
over whether the resources are released, or whether they are not released and the DR
process is therefore aborted.
Taking the workload conditions into consideration
Performing a DR process in a peak-workload period is not practical. You must therefore
think ahead when planning the DR scenarios CoD and workload distribution to ensure
that DR is performed in a phase with little workload.
In planning workload distribution you must take into account that the peak-workload
phases are staggered sufficiently in the partitions of the SX server which alternate in
their use of an XSB alternately .
Sufficient spare resources should be kept available to be able to replace failed
resources if a hardware failure occurs during the peak-workload phase.
State of BS2000/VM2000
BS2000/VM2000 must be in a state which is compatible with the initiation of the DR
process.
This is the case when one of the following points applies:
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BS2000/VM2000 is started and agrees that the DR process should be initiated.
This is, for example, the case when BS2000/VM2000 has entered the System Ready
state after an IPL.
No IPL was performed after X2000 was started.
BS2000/VM2000 is shut down and set no DR lock when it shut down.
For example, the DR lock is set if a SLED is performed after system shutdown
(abnormal shutdown procedure, SETS).
The DR lock was canceled with the bs2dr -reset command.
HIPLEX MSCF must permit the DR process.
The BS2000/VM2000 resources which are lost with DR-disconnect should not be
reserved by the system or by applications. In each case BS2000/VM2000 decides
whether it will withdraw a resource from the system or from an application or abort
the DR process.
Dynamic Reconfiguration
U41272-J-Z385-3-76