Smart Array Sas P400 Controller; Networking Technologies; Tcp Offload Engine - HP DL585 - ProLiant - G2 Technology Brief

Smart Array SAS P400 Controller

The DL585 G2 includes a Smart Array P400 Controller which supports SAS storage. Some
configurations of the DL585 G2 include a battery-backed write cache (BBWC) on the P400 controller.
For models that do not include the BBWC, it is available as an option. The battery will last two days
without receiving any power from the computer.
The BBWC buffers disk writes so that disk I/O can be handled efficiently. The battery is needed in
case of an unexpected system shutdown so that the information in the buffer will not be lost. In the
event of a complete system failure, the controller and disks can be moved to a different server, where
the controller will flush out the cache to the disks when power is restored. In the case of a controller
failure, the cache module and disks can be removed from the failed controller and installed on a
working controller, where the cache will be flushed out to the disks.
The Smart Array P400 supports RAID levels 0, 1, 1+0 and 5. RAID 6 (double parity) is available and
does require the BBWC. Mirror splitting is available for RAID 1 arrays. This functionality allows the
user to split a RAID 1 mirror into two separate RAID 0 arrays (breaking the mirror).
The BBWC is required for capacity expansion functionality, which allows the user to add a physical
disk to an existing array. The controller then recalculates parity and balances the data across the
disks. During the expansion, data and logical structures on the array are preserved.
The P400 controller supports a recovery ROM for failing back to the previous valid ROM if an attempt
to flash the controller's ROM should fail. Online Drive Flashing is also supported. With Online Drive
Flashing, disk drive firmware updates can be pre-loaded onto the controller. At the next reboot, the
controller will flash the firmware on the hard drives.

Networking technologies

The DL585 G2 includes an embedded, dual-port, NC371i multifunction, gigabit Ethernet network
interface controller (NIC). Technologies enabled by the NC371i include TCP Offload Engine (TOE),
including support for Accelerated iSCSI through an optional licensing kit.

TCP Offload Engine

Network bandwidth has improved steadily since the early days of TCP/IP networking. Along with this
improvement in speed has come increased the demand for CPU cycles to manage the network
protocol stack. A busy, full-duplex gigabit Ethernet connection can consume the available computing
power of a 1-GHz Pentium 4 processor. Unfortunately, this means that even a modern, high-powered
CPU will show degraded performance in processing application instructions while data is being
transferred onto or off of the network. Computers most susceptible to this problem are application,
web, and file servers that have a high number of concurrent connections.
To reduce this burden on the CPU, the embedded NC371i network controller in the DL585 G2 is
designed with TOE capabilities. TOE NICs are designed with on-board logic to process common and
repetitive tasks of TCP network traffic. Because the CPU does not have to devote cycles to processing
these tasks, it can be used more efficiently to significantly increase application performance on
servers attached to gigabit Ethernet networks.
TOE is supported on Microsoft Windows Server 2003 with the Scalable Networking Pack installed.
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