HP NetRAID Product Paper

Drive Roaming The HP NetRAID controller
stores configuration information both in NVRAM
(non-volatile RAM) on the controller and on the
disk drives. It protects the configuration settings
in the event of a disk drive or controller failure.
Drive roaming allows administrators to
physically move drives within a server or
between servers without losing valuable
configuration information. (Configuration
information can also be stored on a file, a
network drive, or a floppy disk.) Unlike online
capacity expansion and RAID level migration,
drive roaming is done at system boot-up time. If a
server fails, the disk drives can be moved to a
backup server and inserted in any order. The HP
NetRAID controller in the backup server will read
the configuration from the drives and your
system will be up and running.
Flexibility and Availability
With the HP NetRAID Adapter, reliability in case
of disk or power failures is provided by three
special features: hot swaps, hot spares, and
battery backup for cache. All three techniques
offer significant advantages in restoring normal
operation after a failure, especially in conjunction
with server management systems and servers in
remote environments. High reliability is also
made possible by the three additional RAID
levels—RAID-10, RAID-30, and RAID-50—that the
HP NetRAID Adapter provides. With these RAID
levels, two physical disk drive failures (one in
each array) can occur and data will still be
protected.
Hot-Swap Drives Hot-swap drives allow server
drives to be easily removed and replaced without
powering down the server. Fixed drives are
typically cabled into server enclosures. Replacing
a fixed drive involves powering down the server,
opening the enclosure, unplugging the drive’s
data and power cables, installing the new drive,
and putting everything back together again. Hot-
swap drives work just like drawers—you slide
them in and out, with all power and cabling
issues being handled transparently. In addition to
ease of set up, hot-swap drives can allow much
faster recovery from a disk failure.
AutoRebuild with Hot Spares Hot spare drives
provide totally unattended recovery from a drive
failure. A hot spare is an idle, powered-on,
standby disk module ready for use should
another disk module fail. When a disk fails, the
DAC automatically replaces and rebuilds the data
from the failed disk onto the hot spare disk. The
HP NetRAID controller allows a single hot spare
to be used across multiple channels, lowering the
cost of overhead associated with high
availability. Multiple hot spares may also be
defined, allowing you to trade off high availability
and cost.
Battery Backup for Cache Memory The HP
NetRAID Adapter includes a 60-hour battery
backup for 4MB of onboard cache, providing
protection from power supply interruptions to the
server and preventing cache data loss. It is worth
noting that 4MB is an optimal cache size for
performance as well as for maximizing battery
life. A larger cache would substantially reduce
the length of the battery backup window.
Audible alert The HP NetRAID Adapter has an
onboard tone generator to sound an audible
alarm when a drive fails, is degraded, or is
rebuilt. The audible alert is especially useful in an
environment with many servers in one area. It
alerts the operator to the problem so that action
can be taken quickly. The alarm can be enabled,
disabled, or temporarily silenced.
Configuration and Management
No matter how data is stored on disks, the ability
to easily configure and manage the disk system is
critical. The HP NetRAID Assistant provides an
easy-to-use, object-oriented graphical user
interface (GUI) that makes installation,
configuration and management easy. During
configuration, HP NetRAID Assistant makes it
easy to define disk arrays and logical drives,
designate hot spares, and set the rebuild rate and
various logical drive parameters. After
configuration, the HP NetRAID Assistant makes
it possible to monitor and manage physical and
logical drives, add capacity, and migrate RAID
levels on the fly.
For remote management, HP NetRAID Assistant
can be run on a Microsoft Windows NT or
Windows 95 client and can monitor all DACs in
all Microsoft Windows NT or Novell NetWare
servers on the network. Password authentication
protects the security of the server.
The HP NetRAID Adapter provides SNMP agent
capability under Microsoft Windows NT, Novell
NetWare, IBM OS/2, and SCO UNIX to allow for
centralized event notification through the HP