Recovering Data From The Flash-Backed Cache; Entry Level Raid Solutions; Software Raid; Zero Memory Raid - HP 273914-B21 - Smart Array 6404/256 RAID Controller Technology Brief

Recovering data from the flash-backed cache

When system power is present, the FPGA on FBWC is in its idle state. In the idle state, the FPGA
simply monitors the voltage statuses, the resets, and the control signals managed by the Smart Array
controller. The FPGA's DDR2 I/O pins are held in "tri-state," equivalent to a disabled mode, to avoid
bus contention. When system power is lost, the FPGA waits for the Smart Array controller's clock
enable signal to transition to low, signaling that the controller has stopped driving the DDR2 bus. At
this time, the FPGA assumes control of the bus and begins moving data from the DRAMs to the non-
volatile flash memory. Upon the next power up, the FPGA then restores the cache by moving data
from the flash memory to the DRAMs.
Once cache has been restored to the DRAMs, the Smart Array controller verifies that the data has
been retained correctly. If so, the data is transferred to the disk disk drives.

Entry level RAID solutions

Software RAID

HP has developed a software RAID solution based on the Smart Array firmware. The B110i SATA
Software RAID supports the ACU, ACU-CLI (command line tool), SNMP agents, and Web-Based
Enterprise Management (WBEM) providers.
The B110i features an OS-specific driver from HP that uses the embedded ICH10R controller. The
B110i supports RAID 0, 1, and 1+0 and a maximum of two logical drives. The B110i supports up to
four 1.5G or 3G SATA drives. Administrators can move drives to a Smart Array controller in a
seamless procedure that maintains the user data and RAID configuration.
The ProLiant DL320 G6 server supports the B110i. For a listing of the complete feature set and
support information for the B110i SATA Software RAID, download the B110i user guide at
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01706551/c01706551.pdf

Zero Memory RAID

Using Zero Memory RAID (ZMR), administrators can create a RAID 0-1 configuration without
additional memory. ZMR uses memory embedded in the controller, approximately 1K in size, and
supports limited configurations. ZMR supports up to eight drives in Zero Memory Mode, or seven
drives and one tape drive. ZMR does not include caching; however, all systems can be upgraded to a
BBWC memory module that can significantly increase performance.
ZMR is supported on present generation Smart Array controllers for internal, direct connections only.
This includes the Smart Array P410, P410i, P212, and P712 controllers. Consequently, the P212
controller does not include ZMR on the external connector. Modular Smart Array (MSA) products are
not supported in ZMR mode.
NOTE:
The P212 controller can only be upgraded to 256 MB BBWC, so it does not support
512 MB BBWC.
NOTE:
Smart Array Advanced Pack is not available on Zero Memory configurations.
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