Developing rma requirements

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: MeanTime Between Failures
 MTBCF: MeanTime 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 : MeanTime 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: MeanTimeTo 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 ResponseTime(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

Developing rma requirements

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