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section 2
reliability characteristics of hp's
va7000 series
redundant, hot swappable controllers, fans,
•
power supplies, and an internal fibre-channel
hub eliminates planned downtime
online firmware and capacity upgrade
•
using mixed capacity disk drives
Checksum algorithm used for end-to-end
•
data and data-path protection against
data corruption
double parity supports recovery from two
•
simultaneous disk failures (RAID 5DP)
error Correction Code (ECC) protects mirrored
•
cache from corruption before writing to disk
three-day battery backup protects user data
•
in cache from power outages and disasters
phone-home
capability
•
through hp's Predictive Support programs
and Event Monitoring Services (EMS)
"Redundancy groups" are physical disks that contain
redundant (copies of) data, defined by the RAID
type assigned to the data. Each redundancy
group is divided into LUNs, addressable by a host.
The VA7100 supports only one "redundancy
group" with each of the 15 disk drives in the
enclosure addressable by both controllers with
no physical restrictions. The two fibre-channel
loops (one to each controller) include a transmit
line and a receive line for the transfer of data to
and from the controller. Controller-to-controller
communication and loop failover occur via an
internal N-way bus.
The VA7400 supports two redundancy groups in
which one controller manages access to one redundancy
group (consisting of all the odd-numbered disk
slots) and the other controller to the second group
"hp extends virtualization to the array"
is
provided
2.2
—by D.H. Brown Associates, Inc.
(consisting of all the even-numbered disk slots). Data
movement and failover occur in the same manner
as in the VA7100.
The variation in data management at the array level
provides great flexibility in matching performance
to application need. Self-tuning enables immediate
response to data and application variables
ensuring more work completed per transaction
and maintaining more consistent service-level
performance. RAID 1+0 uses a large number of
disks in a single configuration to deliver strong
performance to selected LUNs. It does so, however,
at the expense of additional space for mirroring
the data. RAID 5DP incurs a performance penalty
for write operations and can affect system
performance if frequent updates to large volumes
of data are required. Its advantage is in the data
redundancy provided and the improved cost
efficiency vs. mirroring. Dual-redundancy groups
in the VA7400 enhance the efficiency of data
movement through the controllers, improving
system performance.
Copyright © 2001 by D.H. Brown Associates, Inc.
2
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