Hitachi Virtual Storage Platform, User And Reference Manual

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Hitachi VSP User and Reference Guide
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System Components
As shown in the figure above, the fan assemblies on both the front and rear
sides of the drive chassis swing out and away from the unit to allow access
to the disk drives. The three-speed fans in the drive chassis are
thermostatically controlled by a temperature sensor (thermistor) in the
unit. The sensor measures the temperature of the exhaust air from the unit
and sets the fan speed as needed to maintain the unit temperature within
a preset range. When the unit is not busy and cools down, the fan speed is
reduced, saving energy and reducing the noise level of the unit.
When the fan assemblies are opened, the power to the fans is automatically
switched off and the fans stop rotating. This helps prevent possible injury
because there is no protective screen on the back side of the fans.
Flash components
This section includes information on the Hitachi Accelerated Flash storage
components, including the flash module, flash box, and flash chassis.
Flash module
The flash module (factory designation FMD) is a Hitachi custom-designed
and manufactured enterprise class solid state storage module. It uses a
high performance, custom ASIC flash controller and standard flash memory
chips in an implementation that exceeds the performance of expensive SLC
SSDs, but costs less than inexpensive MLC SSDs. The flash module greatly
improves the performance and solid state storage capacity of the VSP
system, while significantly reducing the cost per TB of storage.
Even in the initial capacity of 1.6 TB, the flash module outperforms both
HGST MLC and SLC flash drives, has a longer service life, requires less
power per TB, and generates less heat per TB than SSDs. The VSP currently
supports both 1.6 TB and 3.2 TB flash modules.
Flash modules can be used instead of or in addition to disk and flash drives,
but they are installed in a flash chassis composed of a cluster of four flash
boxes. The next section describes the flash box.
Figure 3-6 Flash module