IBM System Storage DS4000, Руководство по оборудованию

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IBM Midrange System Storage Hardware Guide
3.5.1 DS5020 controller architecture
The DS5020 storage subsystem uses almost the same controller architecture as the DS4700
does (see Figure 3-41) with a few minor differences.
򐂰 Uses a faster XOR engine (1.2 GHz vs. 667 MHz on DS4700).
򐂰 One optional host interface (either dual port iSCSI or dual port 8 Gbps FC).
򐂰 The internal bus is PCI-E x8 (PCI-X on DS4700).
򐂰
Flash drives are used to destage dirty data from the cache in case of a power loss.
The heart of the controller is the 1.2 GHz XOR raid processor, which has improved speed
compared to the DS4700 667 Mhz Xscale processor. The standard 8 Gbps host port and the
optional Host Interface Cards in Figure 3-42 on page 69 and Figure 3-43 on page 69 share
the same PCI-E x8 bus to transfer their data to the XOR chip. The main FC switch on the
controller mainboard processes the FC traffic for the drive channels as well as for the two
standard host channels.
The backup battery unit provides power to back up the cache memory of each controller onto
flash drives in the event of a power failure.
To distribute the data to the drives, a chip called “switch-on-chip” (SOC) is used to switch the
data directly to their internal destination drive or the external drive channel.
Both controllers connect indirectly via the drive channel.
Figure 3-41 DS5020 controller architecture breakout
DS5020 controller architecture
Interface for
optional HIC
Two standard 8 Gbps
FC host ports
Faster XOR
Raid processor
4 Gbps drive
channel
Internal dual
ported drive bays
FC drive channel switch
in backplane (SOC)
Main fibre channel interface chip
Flash drive for
dirty data
8Gb/s