6 mis-availability
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This document discusses key concepts related to information system availability, including availability, uptime, fault tolerance, and high availability. It defines these terms and explains how availability is measured. The document also identifies 10 key components that contribute to high availability and discusses limitations to high availability approaches. Finally, it presents the "7 Rs of Availability" - redundancy, reliability, recoverability, repairability, reputation, responsiveness, and robustness.
6 mis-availability
- 1. Ridi Ferdiana | ridi@acm.org Version 1.0.0
- 2. Availability is the process of optimizing the readiness of information systems by accurately measuring, analyzing, and reducing outages to information systems.
- 3. Similarity Measured by time in a year / month The difference Uptime is a measure of the time that individual components within a production system are functionally operating Availability focuses on the production system as a whole.
- 5. Slow response refers to unacceptably long periods of time for an online transaction to complete processing and return results to the user Downtime refers to the total inoperability of a hardware device, a software routine, or some other critical component of a system that results in the outage of a production application.
- 6. High availability refers to the design of a production environment such that all single points of failure are removed through redundancy to eliminate production outages Fault tolerant refers to a production environment in which all hardware and software components are duplicated such that they can automatically failover to their backup component in the event of a fault
- 9. Percent Availability = (Hours Agreed Up - Hours Down)/Hours Agreed Up
- 10. Budget limitations Component failures Faulty code Human error Flawed design Natural disasters Unforeseen business shifts (such as mergers, downturns, political changes)
- 11. Redundancy Power supplies Multiple processors Segmented memory Redundant disks Reliability Logs Management Feedback Analyst Recoverability Network Avail. System Restart System Switch Over Repairability MTBF = sampling interval / # of failures during sampling interval MTTR = sum of repair times / # of failures
- 13. Reputation Percent market share Industrial comment Publication Review Track records Customer Reference Responsiveness In house support Recovery disk Well trained user Robustness Technical changes: Platform, Product, Services, Customer Personal changes: Turnover, Expansion, Rotation Business changes: New direction, Acquisitions, Merger
- 17. Learning the key terms : Availability, Up Time, Fault Tolerant, and High Availability 10 key components of high availability Key skills that needed to handle the IS Availability Measuring Availability from SLA High Availability Limitation 7 Rs of Availability Assesing Availability