Dell PowerVault MD3200i Series - Controller Architecture

DELL PowerVault MD3200i/MD3220i Technical Guide Book
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Controller Architecture
Figure 1. RAID controller architecture of the MD3200i controller.
The RAID controllers are the “engines” or the “brains” of the MD3200i and MD3220i storage arrays.
They perform the RAID calculations, control the I/O movement, communicate with the management
client, store the firmware, and protect data until it can be written safely to the hard disk drives. The
MD3200i’s architecture is designed to excel in multi-host systems environments. Its I/O system core
provides built-in hardware XOR for high-speed RAID parity calculations – enabling it to easily handle
very compute-intensive tasks. Each RAID controller contains 2GB of cache for a total of 4GB of cache
in a dual controller configuration which is mirrored with the other controller’s cache for high
availability. In the event of a power failure, the controllers are protected with battery assisted
persistent cache backup which destages cache to non-volatile media for indefinite safe keeping.
Each controller has a 36-port 6 Gb/s SAS expander that provides access to the drives in the MD3200i or
MD3220i enclosure. The SAS expanders enable each controller to access all of the drive ports creating
active/active drives loops that provide both controllers redundant access to all attached disk drives.
SAS
Exp
SBB
2.0 Compliant Connector
2GB
DDR-II
1Gb Eth
NIC
RJ
45
I2C
32-lane 8-port
PCI-E Switch
PCI-E
PCI-E
DDR-II
X4
X24
(Drives)
X4
X4
(Alt Ctrl)
BBU
Cache Offload
Assembly
PCI-E
SD
FPGA
Flash
16 Bit Parallel Bus
NVSRAM
PCI-E PCI-E
X4
(Alt Ctrl)
Flash
800MHz
Power PC
6Gb SAS
36 Port
Expander
iSCSI TOE
RJ45
RJ45 RJ45
RJ45