© 2006 Hewlett-Packard Development Company, L.P.The information contained herein is subject to change without notice

HP and Carrier Network System Availability

Lee Hines

Hewlett Packard Software Division

6 April 10, 2023

Availability, outages and the impacts of reliable networks

7 April 10, 2023

“There was a power outage at a department store yesterday. Twenty people were trapped on the escalators.”

- Stephen Wright

Measuring availability

• Based on 24x7 operations, • Planned and unplanned outages.

Percent of availability*

99% 99.9% 99.99% 99.999% 99.9999% 99.99999%

Outageminutes/

year~5,000 ~500 ~50 ~5 ~.5 ~.05

Outageto users

3.65 days 8.8 hrs. ~50 min. 5 min. 30 sec. 3 sec.

Carrier network impacts from availability

HP NonStop server availability

HP NonStop availability and location based services

12 April 10, 2023

Increasing the availability – toward Seven, Eight & Nine 9’s

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 take-over

• 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

13 April 10, 2023

14 April 10, 2023

Dual to Triple-Mode RedundancyDual-Mode Redundancy = Five 9’s Availability Triple-Mode Redundancy = Seven 9’s Availability

Reliability, Availability, Scalability