Fujitsu Siemens Computers S60 - Manual (Page 68)

60 U41221-J-Z156-1-74
Power connection via UPS Connections
9.4 Power connection via UPS
The availability of the storage subsystem can be improved further by using
Uninterrupted Power Supplies (UPS) and/or a Redundant PowerSwitch.
I
IWhen 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 FFx-RAID
Controller to switch into the degraded mode and the current cache content will
be secured (duration approx. 5 minutes).
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 FFx-RAID Controller is deactivated.
I
Phase redundancy can be easily achieved by the additional use of a
Redundant PowerSwitch.