LO3

LO3

1. Types of servers

   • File
     • Useful for organisations that need to hold/manage large no. of files
       • Stores, indexes, remembers locaton and takes responsibilty of files
         • Only allows those with access rights to see files, makes regular, secure back ups
   • Printer
     • Control printers on a network, allow groups of employees to send print requests to specific printers
       • Reroute from broken down printers, organise priority of print requests and manage the print queue across availble printers
   • Application
     • organise installation, operation and monitoring of all applications being run on the server.
       • Some applications can be shared among users like word processing software and spreadsheets
         • Server also manages security for restricted software such as financial and human resources software
   • Database
     • Application server specilised in databases
       • Manages multiple users/databases
         • database architecture independant, they manage all activities wheather for relationship databases, flat file databases or object- orientated ones
   • Web
     • Refers to hardware and software of server
       • Internet server that connects to HTTP requests to deliver content and services from client
   • Mail
     • Acts as an electronic post office
       • Recieves emails from users and forwards them to recipients
         • Normally use SMTP, POP3 or IMAP to recieve it
   • Hypervisor
     • Written for a particular processor that manages multiple operationg systems on the network
       • Manages resources like processors, memory and devicesd to determine efficientcy on the network to prevent clashes

2. Virtualisation

   • Create a simulated or virtual network, computer or server using software
     • 1970s, harware/operating system closely linked together so only some applicatiions can run simultaneously to prevent registry problems
     • To operate additional applications, additional servers have to be installed with their own applications
       • Server virtualisation allows for single physicla servers to run several application within what appears to be their own servers. This tends to run more slowly but is safer and more secure in case of failures
   • Storage virtualisation separates physical storage from logical storage, I can take two forms
     • Block level - Allows SAN (Storage area network) to use numerous storage arrays across the network as if they were a single array
     • File level - Allows NAS (Network Attached Storage) and removes link between the data items and their physical locations on a file server
     • Cloud computer IS NOT virtualisation, The cloud uses existing technology to deliver services, such as security, storage and data manipulation, it is a utility to users in a network
     • Hybrid cloud computing is a mixture of private, public and locally owned services. Organisations can change and adjust their usage more effectively
   • Advantages
     • Cost saving
       • Less hardware needed
         • Reduces amount of physical space needed
           • More flexible way to run applications
             • Operating systems and applications could potentially be run on single piece of hardware
               • Easier to back up
                 • Quick disaster recovery
     • Disadvantages
       • Large upfront costs
         • Licenses need to be bought
           • Number of operating systems that can run are limited
             • Difficult to handle graphics and HD video

3. Network charcteristics

   • Peer-to-peer
     • Each computer is linked to one or more other computers directly rather than through the server. All data is controlled by both machines involved in the communication phase
   • Star
     • All computer communicate through a central hub, All transmissions received by hub are then sent to every computer in the network If one computer crashes athe other computers are unaffected but if the hub goes down everything goes down. Cost of cabling can be very expensive
   • Bus
     • All devices are connected to a central cable with terminators are each end, Attaching new devices is easy, if one machine fails the rest do not
       • Cheaper than star topology, transmissions go both ways
         • Findign problems is harder, cable breaks and the whole network is lost, high chance of data collision
   • Ring
     • 1 direction communication through cable. Message is recieved by each computer and passed on if necessary, each computer boosts the signal to stop degradation
       • Rings sue tokens to prevent problems of multiple messages colliding. Packet of data constantly goes around the ring and computers will attach data to the token as it passes. Computer can only add data is the token is free of data
     • Token ring LANs
   • Mesh
     • Total
       • Every node is connected to every other node, if connection stops working the signal is re routed
     • Partial
       • Some nodes are connected to other nodes while others are connected to all. Cheaper than total mesh but could face problems is signal can re route
   • Client server
     • One computer or specilise server will have all applicatios and storage and will provide services to the computers in the network

4. Connectivity

   • LAN
     • Ethernet netwrok LANs
       • Half duplex LANs allow communication in both directions but not at the same time as collisions could occur and crahs the network
         • To avoid this, a media access Control method called CSMA/CD (Carrier Sense Multiple Access with Collision Detection). It works by detcting collisions in the network and forcing them to wait random amounts of time before sending data to stop error from happening
       • WAN
         • Wide Area Network can be international network
         • MAN
           • Metropolitan Area Network network that spreads over a city/county
             • Each network has their own set of rules/protocols to ensure that generic devices can communicate
               • ADSL/ISDN are examples that communicate data over a copper wire phone system
               • However leased lines provide a fixed bandwidth that operate outside of publically availble (inter)national wires. Bandwidth is only avavilble to lease and avoids unnecessary slowdowns
           • Satellites
             • Point-to-multipoint communication systems that recieve data and send to multiple recievers
               • Satellites can be moved to other locations very quickly to deal with heavy data traffic. However due to the large distance (75,000 KM) there is a delay in communication and data packets can be lost

5. Business systems

   • MIS
     • CRM
       • SOP
         • Help Desk
           • Large organisations need to have a knowledgeable person ready to solve any problem. complex problems can be solbved by technitians visiting the location or remoteley accesing the problem
           • Limitations: Costly to set up in-house with hardware, software and staffing, Costly if setting up through 3rd party, issues with availbility (bank holidays? 24 hour service?), Loss of service can occur through breakdon of communications systems
         • Detailed step by step guides on how functions should be carried out t6o ensure consistency.accuracy within an organisation
         • Same outcome while leavin an audit trail in case of disputes.external investigations by regulatory bodies
         • Limitations include: Imposing restrictions result in inflexible practide + lack of innovation, Too much time spent on admin rather than doing the job, SOP having updated to reflect new stratutory/regulatory requirements, Lack of version control where individuals could be using the wrong SOP for a task
       • Process that tracks how businesses interact wuth current/potential customers, holds records of cliebnt communications, meetings and documentsthose with access rights have this infoamation availble
       • CRM allows for: Contact details, Customer histories, Potential leads for new cutomers, Potential leads for new services
       • CRM primarily aimes at sales/customer support functions, Marketers also use CRM to aid understanding of current sales trends, prospective sales and forecasting future tends.
       • Limitations include: Limits on size/data storage of emails, Intergrational difficulties with other systems/Lack of training leading to poor data entry and incorrect data, Resistance staff who believe that using digital infotrmation ratehr tahn face to face meetings with clients reduces their ability to understand subtle communication behaviours
     • Management information systems, software/hardware used by managers to obtain necessary information for accurate decision making and monitoring the effectivenss of decisions
       • The system continuously gatherin internal/external data to refine and organise it in one or more databases where it is interrogated by those with access rights
         • Can create reports and other documents, spreadsheets and strategic decision support systems Functional systems cuch as those for marketing, sales or production
           • MIS can provide: Status of the organisation, Areas of improvement (Rising sales), Areas of risk (Loss of makret share), Personal or group responsibility for risk or failure
             • Their limitations are: Cost of creating/installation, Poor/inflexible design which do not meet company needs, Data is out of date/incomplete leads to incorrect results