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IT Infrastructure Summary - Score 7
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The summary of the book for the exam IT infrastructure for the HBO program Software Engineering and Development. The score obtained is a 7.
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By: frankverschelling • 2 year ago
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IT-infrastructuur samenvattingLeerdoelen
1. IT-infrastructuuronderdelen vertalen naar eigen organisatie (1).
2. de plaats van IaaS binnen de cloud verklaren (1).
3. de beschikbaarheid van IT-infrastructuur afleiden (1).
4. de performance van IT-infrastructuur verklaren (1).
1 t/m 5 en 14.6
5. verklaren op welke OSI-laag een component actief is (2).
6. de netwerkvirtualisatiemogelijkheden becommentariëren (2).
7. Software Defined Networking verhelderen (2).
8. de netwerkarchitectuurmogelijkheden om beschikbaarheid te verhogen preciseren (2).
9. netwerkperformanceconcepten verklaren (2).
8 t/m 8.5
SDN tot en met III.D
10. de meestgebruikte processorbouwblokken (exclusief mainframes, midrange en
supercomputers) beschrijven (3).
11. de processorbeschikbaarheid en -performance herkennen (3).
12. de operatingsysteembouwblokken benoemen (3).
13. de operatingsysteembeschikbaarheid en -performance herkennen (3).
10.2 t/m 10.2.6, 10.2.9, 10.3, 10.4 en 11.2 t/m 11.4
14. datacenterbouwblokken benoemen (4).
15. de beschikbaarheid en performance van datacenters beschrijven (4).
16. storagebouwblokken herkennen (4).
17. storagebeschikbaarheid onderkennen (4).
18. storageperformance onderkennen (4). Chapter Remark
7 t/m 7.4 en 9 t/m 9.4 1
2
19. verschillende werkpleksystemen becommentariëren (5).
3
20. werkplekvirtualisatiemogelijkheden preciseren (5).
21. werkplekbeschikbaarheid en -performance vertalen (5). 4
22. de toepasbaarheid van WebRTC illustreren (5). 5
12 t/m 12.5 6
WebRTC 7
8
23. securityconcepten toepassen (6). 9
24. een aanval op IT-infrastructuur illustreren (6). Except 10.2.7,
25. beveiligingsmaatregelen toepassen (6). 10
10.2.8 and 10.2.10
26. de infrastructuur-lifecycle in praktijk brengen (6).
6, 7.5, 8.6, 9.5, 10.5, 11.5, 12.6, 15, 16, 17 en 19
11
SDN III.F 12
14.6
15
16
17
19
1
,Part I: Introduction to IT infrastructure
Chapter 1 The definition of IT infrastructure
Organizations benefit from infrastructure when they want to be more flexible and agile. A solid, scalable
and modular infrastructure provides a firm foundation for agile adaptations.
The market demands a degree of flexibility in the infrastructure. Infrastructures should be constructed
from standardized, modular components.
Architecture is crucial. Architecture is the philosophy that defines the purpose, intent and structure of
the system.
IT infrastructure is dependent on who you ask and what their point of view is.
Chapter 2 The infrastructure model
Infrastructure is defined based on the following building blocks, this model is a simplified version of
reality.
Functional management: Processes / Information building block
Organizations implement business processes to fulfil their mission and vision. Business processes create
and use information. Functional management is the category of systems management that ensures the
system is configured to perform the needed business functions.
Applications management: Applications building block
Three types of applications:
• Client applications typically run on end user devices, browsers, email clients, word processors
• Office applications provide standard server based applications, mail servers, portals,
collaboration tools
• Business specific applications typically highly customized or custom built, Customer Relationship
Management (CRM), Enterprise Resource Planning (ERP), specific business process applications
(FEM)
Applications management is responsible for the configuration and technical operations of the
applications.
Platforms management: Applications platforms building block
Additional services for applications like:
• Front end servers provide interaction to applications by presenting application screens in
browsers
• Application servers act as containers running the actual application
2
, • Connectivity entails FTP servers, Extraction, Transformation and Load (ETL) servers and
Enterprise Service Buses (ESBs)
• Databases or database management systems (DBMSs) provide a way of storing and retrieving
structured data
Applications platforms are typically managed by systems managers specialized in the specific
technology.
Infrastructure management: Infrastructure building blocks
• End user devices: PCs, laptops, mobile phones, printers, etc.
• Operating systems: collection of programs that manage a computer’s internal hardware
• Compute: the physical and virtual computers
• Storage: the systems that store data
• Networking: connects all components
• Datacenters: the locations that host the IT infrastructure hardware
These blocks are not per definition hierarchically related. Infrastructure management includes processes
like IT Infrastructure Library (ITIL) and DevOps, and tools like monitoring, backup and logging.
Non-functional attributes
The functional building blocks are supported by non-functional attributes, these are the effect of the
configuration of each IT system component on all levels.
Part II: Non-functional attributes
Chapter 3 Introduction to non-functional attributes
Better term is quality attributes instead of non-functional attributes.
Non-functional attributes describe the qualitative behavior of a system, rather than specific
functionalities. Some examples:
• Scalability
• Reliability
• Stability
• Testability
• Recoverability
And the most important
• Security
• Performance
• Availability
Non-functional attributes are very important for the successful implementation and use of an IT
infrastructure, but in projects, they rarely get the same attention as the functional services.
Non-functional attributes are very functional but they are not directly related to the primary
functionalities of a system, they do have a fairly large function. Users of systems most of the time do not
state non-functional attributes explicitly, but they do have expectations about them.
Finding the implicit requirements on non-functional attributes (non-functional requirements: NFRs) is
difficult, because what is obvious or taken for granted by the customer or end users is not always
obvious to the designers and builders of the system.
A large part of the budget for building an infrastructure is usually spent in fulfilling non-functional
requirements that are not always clearly defined.
Many of the non-functional attributes of an application are delivered by the infrastructure. This makes it
very important to consider all design decisions when it comes to non-functional attributes.
It is the IT architect’s responsibility to balance conflicting non-functional requirements.
Chapter 4 Availability concepts
No matter how much effort is spent on creating high available infrastructures, there is always a chance
of downtime.
3
, Availability can, in general, only be reported when a system has run for some time. Designing for
availability is a complicated task. Available patterns for design are:
• Failover
• Redundancy
• Structured programming
• Avoiding Single Point of Failures (SPOFs)
• Sound system management
Availability of a system is expressed in a percentage of uptime in a given period of time. Typical
requirements are 99.8% or 99.9% per month.
Five nines (99.999%) is known as carrier grade availability which originates from telecommunication
system components, not full systems!
It is good practice to agree on a maximum frequency of unavailability. You do not want 1 long downtime
or hundreds of 1 minute downtime.
MTBF: Mean Time Between Failures – Average time between failures expressed in hours.
Tests are run on large batches for a short period of time to determine MTBF. It is an extrapolated value
for probable failure of a disk.
MTTR: Mean Time To Repair – Time it takes to recover from failure. This is kept low by having a service
contract with component suppliers. When spares are kept on site MTTR becomes Mean Time To
Replace. Keep MTTR low by introducing automated redundancy and failover.
Both are statistically calculated values.
𝑀𝑇𝐵𝐹
Availability is calculated with: 𝐴 = 𝑀𝑇𝐵𝐹+𝑀𝑇𝑇𝑅 ∙ 100%
As system complexity increases, usually availability decreases. Serial availability is when a failure of one
component causes failure of the whole system.
The availability of the whole system is the multiplication of the availabilities of all components.
𝑛
Availability of redundant components can be calculated with: 𝐴𝑛 𝑐𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡𝑠 = 1 − (1 − 𝐴𝑐𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡 )
Sources of unavailability are:
• Human error – Number 1 reason of unavailability
80% of failures is caused by people or process issues and >50% of these by change,
configuration, release integration and hand-off issues. Most unavailability issues are the result
of actions from system managers. Hackers can create downtime by executing Denial of Service
(DOS) attacks.
• Software bugs – Number 2 reason of unavailability
• Planned maintenance – An SPOF could be introduced when planned maintenance is executed on
a component. When one component of a high available cluster is upgraded while the other
component is not yet upgraded the cluster is not working as a high available cluster.
• Physical defects – Mechanical parts are most likely to break first. Normal usage causes failure
but also external factors like ambient temperature, moist, vibrations and aging. Like all parts, a
power supply will age and slowly loses power capacity, rule of thumb is to calculate a surplus of
25% on the required power.
Bath tub curves – A component failure is most likely when the component is Dead On Arrival
(DOA). If this does not occur it will most likely continue working until the end of its technical life
cycle. This is when the chance of failure rises suddenly.
4
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