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HP and Carrier
Network System
Availability
Lee Hines
Hewlett Packard Software Division
© 2006 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice
Availability,
outages and the
impacts of reliable
networks
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18 July 2015
“There was a power outage at
a department store yesterday.
Twenty people were trapped
on the escalators.”
- Stephen Wright
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18 July 2015
Measuring availability
•
•
Percent of
availability*
99%
99.9%
99.99%
99.999%
99.9999%
99.99999%
Outage
minutes/
year
~5,000
~500
~50
~5
~.5
~.05
Outage
to users
3.65 days
8.8 hrs.
~50 min.
5 min.
30 sec.
3 sec.
Based on 24x7 operations,
Planned and unplanned outages.
Carrier network impacts from availability
HP NonStop server availability
HP NonStop availability and location
based services
Increasing the
availability –
toward Seven,
Eight & Nine 9’s
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18 July 2015
The New NonStop Advanced
Architecture
•
DMR: Dual Modular Redundancy
•
TMR: Triple Modular Redundancy
(HW Availability: seven 9’s)
•
Loose Synchronization (lock-step)
−
Each server runs on its own clock.
−
Each can perform soft error corrections without causing
a miscompare.
•
Self-checked, shared-nothing, transparent takeover
•
Fault Masking – HW Processor failures are
masked and are not visible to all SW except for
lowest level of OS.
−
E.G. an uncorrectable memory error doesn’t stop
the logical processor, it simply stops one
processor element that makes up the logical
processor.
−
Memory has one of the highest rates of failure.
NSAA masks all memory failures.
−
Repairs don’t result in SW disruption either.
•
Fault-tolerant parallel database
•
Application server transaction processing monitors
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18 July 2015
Dual to Triple-Mode Redundancy
Dual-Mode Redundancy = Five 9’s Availability
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18 July 2015
Triple-Mode Redundancy = Seven 9’s Availability
Reliability, Availability, Scalability