Power connection via UPS | Connections |
9.4Power connection via UPS
The availability of the storage subsystem can be improved further by using Uninterrupted Power Supplies (UPS) and/or a Redundant PowerSwitch.
IIWhen the PRIMERGY S60 works in the higher performance Cache Write Back mode, you should use a APC UPS to secure the cache contents (256 MB).
In such cases, the storage subsystem is connected to one of the outlets of the UPS or to the Redundant PowerSwitch. It is generally advisable to connect both the server and the storage subsystem to a shared UPS.
A further possibility to secure the PRIMERGY S60 storage subsystem against power failure is given by the following configuration:
–one power supply unit is connected via an UPS
–the second power supply unit is connected directly (without UPS) to the same phase as the UPS
If a power failure occurs the UPS will secure the first power supply unit, the second (unsecured) power supply unit will fail. This failure causes the
The power supply unit secured over UPS is able to supply the subsystem alone with current. Further data accesses on the storage subsystem are executed however, without cache memory of the controller and are written directly on the hard disks. Data security is ensured if the duration of the power failure is such that the UPS switches the subsystem OFF.
If power failure is restored briefly (before the subsystem was switched OFF), then the failed second power supply unit again becomes active and the degraded mode of the
IPhase redundancy can be easily achieved by the additional use of a Redundant PowerSwitch.
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