DEVELOPING RMA REQUIREMENTS

UNIT – II

Developing RMA Requirements RELIABILITY: (consistency" or "repeatability")

the ability of a system or component to perform its required functions under stated conditions for a specified period of time.

MAINTAINABILITY: performing a successful repair action within a given

time. Used to Maintenance the operations. measures the easy and speed which a system

operational status after a failure occurs. to perform its required functions under stated

conditions for a specified period of time.

AVAILABILITY: in the sense of available useful work. which a system, subsystem or

equipment is in a specified operable and committable state.

MEASURE OF RELIABLILITY: Indicates the frequency of failure

of the network and its components.

MTBF: Mean Time Between Failures

MTBCF: Mean Time Between Mission-Critical Failures

MTBF: Mean Time Between Failure.

A basic measure of reliability. It is the predicted elapsed

time(period of time) between inherent failures of a system during operation.

MTBF is computing the failure rate, which is estimated through testing or analysis in terms of failures per hours of operation.

MTBCF : Mean Time Between Critical Failure. It is sometimes referred to as "mission

reliability" It is a subset of MTBF because it only counts

those failures that result in a mission abort or mission failure.

It is a term used when redundancy exists in a system.

It is often used to differentiate system reliability from series mean time between failure (MTBF).

MEASURE OF MAINTAINABILITY: Statistical measure of the time to

restore the system fully operational status. Once it has experienced a fault.(after repaired)

MTTR: Mean Time To Repair: repairing a failure system consists of detection, isolation (separation) of the failure.

MEASURE OF AVAILABILITY: Relationship between the MTBF, MTBCF,

MTTR. A common measure of availability is

expressed in terms of percent of uptime or downtime.

For example, a request for proposal (RFP) : from a potential customer may state a

required uptime of 99.999% (commonly known as “five nines”).

UP-TIME : Time during the computer is

operational(ON). DOWN-TIME : Time during the computer is NOT

operational(OFF). Availability in terms of uptime and

downtime is measured Per week, per month, or per year based on total amount of time for that period.

Analyzing a network’s availability gives us the

ability to schedule preventive maintenance and replace.Other measures of availability include uptime, downtime, error, and loss rates.

The relationship shown as:

A = (MTBCF) / (MTBCF + MTTR)OR

A = (MTBF) / (MTBF + MTTR)

UPTIME MEASURED OVER DIFFERENT TIME PERIODES

UPTIME: 99% : system to be down quite a bit of

time. 99.9% : 10m applications

stalling(enclose/stand) for several seconds.

99.99% : covers uptime requirements. 9.999% : system being to push

operational limits, network is highly reliable.

DOWNTIME : 99% : considered as low performance.

Measuring uptime

Services are measurable , configurable and verifiable within the system.

Measuring uptime divided into 3 parts: When should it be measured? Where should it be measured? How should it be measured?

Developing DELAY requirements: Interaction Delay(INTD) Human Response Time(HRT) Network Propagation Delay(NPD) End – To – End delay Rountrip Delay Delay variations

Developing CAPACITY requirements

Estimates Data Rates: PDR – peak data rate. MDR – Minimum data rate. SDR – sustained data rate.

Developing supplement : Operational suitability Supportability RMA Workforce