HP AutoRAID 12H manual Reliability characteristics of hp’s, Va7000 series

section 2	“hp extends virtualization to the array”
	—by D.H. Brown Associates, Inc.
reliability characteristics of hp’s	(consisting of all the even-numbered disk slots). Data
va7000 series	movement and failover occur in the same manner
• redundant, hot swappable controllers, fans,	as in the VA7100.	2
	The variation in data management at the array level
power supplies, and an internal fibre-channel
hub eliminates planned downtime	provides great flexibility in matching performance
• online firmware and capacity upgrade	to application need. Self-tuning enables immediate
using mixed capacity disk drives	response to data and application variables
• Checksum algorithm used for end-to-end	ensuring more work completed per transaction
data and data-path protection against	and maintaining more consistent service-level
data corruption	performance. RAID 1+0 uses a large number of
• double parity supports recovery from two	disks in a single configuration to deliver strong
simultaneous disk failures (RAID 5DP)	performance to selected LUNs. It does so, however,
• error Correction Code (ECC) protects mirrored	at the expense of additional space for mirroring
cache from corruption before writing to disk	the data. RAID 5DP incurs a performance penalty
• three-day battery backup protects user data	for write operations and can affect system
in cache from power outages and disasters	performance if frequent updates to large volumes
• phone-home capability is provided	of data are required. Its advantage is in the data
	redundancy provided and the improved cost
through hp’s Predictive Support programs
and Event Monitoring Services (EMS)	efficiency vs. mirroring. Dual-redundancy groups
	in the VA7400 enhance the efficiency of data
“Redundancy groups” are physical disks that contain	movement through	the controllers, improving

redundant (copies of) data, defined by the RAID	system performance.
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
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	Copyright © 2001 by D.H. Brown Associates, Inc.

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