Hitachi 9900 Series - Manual (Page 34)

Hitachi High-Availability
Software Improves
Application Service Levels
An Overview of High-Availability (HA) Computing Software
It is increasingly important for a business to support continued access to global
information 24 hours a day, 7 days a week. What’s more, careers often depend on the
availability of service levels provided by IT to the enterprise.
In computer science, availability refers to the degree to which a system or resource is
capable of performing its normal function. Availability is measured in terms of Mean Time
Between Failure (MTBF) divided by MTBF plus the Mean Time to Repair (MTTR).
• AVAILABILITY = MTBF / (MTBF+MTTR).
For example, a server which fails on average once every 5,000 hours and takes an
average of two hours to diagnose, replace faulty components and reboot, would have an
availability rating of 5,000/(5,000 + 2) = 99.96%. This would correspond to a Level 3
rating using the Scale of 9s.
Software products contribute to High-Availability Computing
Many factors can cause unplanned downtime. The Hitachi Freedom Storage ™
Lightning 9900 ™ has been designed to eliminate as many of these factors as possible in
both hardware redundancy, on-line replaceable components, and software data copy
functions to allow copies of data at other locations either locally or remotely so that
processing can continue in the event of an outage.
Backup and restore procedures and products also contribute dramatically to computer
system availability by reducing the time to restore operations in the event of an outage.
Hitachi has teamed with industry-leading storage management software providers
such as Tantian Technologies ® and VERITAS ® Software of Mountain View, California to
provide world-class high-availability solutions. These solutions contribute to the fact that
customers and analysts alike regard Hitachi Freedom Storage
™ systems as having the highest
availability in the industry.
The Lightning 9900 ™ has an Advanced Availability Profile compared to
Competitive Products
The Lightning 9900 ™ was designed with maximum emphasis on high-availability
computing for today’s most critical enterprises. Figure 21 highlights some of the many
advantages in high-availability design that the Lightning 9900
™ has over other enterprise
storage products.
• Active dual-ported disk drives instead of single-port drives or active/passive
dual-ported drives.
• Redundant active components throughout the system combined with automatic
fail-over architecture.
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Availability refers to the
degree to which a system
or resource is capable of
performing its normal
function.
Customers and analysts
alike regard Hitachi
Freedom Storage systems
as having the highest
availability in the
industry.