Distributed Systems Assignment
Due date: 12 October 2018
Multitask—OS that allows a computer to run two or more programs simultaneously. With Windows 7 a user can run 2 application programs or more (Playing media player and running a word document) at the same time, this makes windows 7 a multitasking OS.
Real time OS–Interacts directly with user and responds immediately. You can use windows 7 to calculate area of a room or sum of numbers and you will get the answer instantly therefore windows 7 is a real time OS.
Multiuser—OS designed to allow multiple users who are getting access to computer hardware and software facilities at the same time. In windows 7 more than 2 users can access computer/OS hardware and software facilities at the same time.
Device driver is a Computer software that provide the operating system and application software access to specific computer hardware devices such as keyboards, monitors. Device driver allows the user to interface with hardware devices by translating computer code to actions that is displayed on the screen..3.
OS- software that supports a computer’s basic functions, such as scheduling tasks and managing the hardware and other software on a computer.
Application software- any program that is designed for the end user to run on the computer.
4. Apple Mac OS has specific hardware requirements such as Intel core m3 with i5 processor, you cannot install it on any host, and also Mac OS X is built on BSD UNIX (the Darwin distribution) and OS built on BSD can’t be installed in just any PC.
In multitasking, the CPU switches between programs, giving the appearance that all programs are running simultaneously. In task switching, the CPU does not switch back and forth, but executes only one program at a time. MAC performed tasks through task-switching but it switched between tasks fast without the user having to wait (or realizing) until it switches to another task, for this reason Mac appeared as a multitasking OS
6. Unix Ubuntu is a free server OS with a GUI interface.
The CPU is the computational chip that performs computer’s logical work.
A processor is the part of a CPU that reads very basic instructions such as reading data from memory. The core is the section of the processor that actually does executing of instructions read by the processor.
8. Complex Instruction Set Computing (CISC)
Reduced Instruction Set Computing (RISC)
Advantage You do not need hardware that is designed specifically for certain purposes. This architecture uses smaller chips, thus reducing per-chip cost.
Disadvantage There is complex need for hardware that is required to perform many functions
RISC processors need very fast memory to feed various instructions.
9. Internal clock speed-The speed at which the CPU executes internal commands.
External clock speed-The speed at which the processor communicates with the memory and other devices in the computer
Transfer = (external clock speed*size of databus)
11. Block allocation keeps track of where specific files are on the disk by dividing the disk into logical blocks that correlate to sectors and tracks on the disk. File systems use block allocation to keep a record of where files are stored on a disk.
Operating System Windows Mac OS UNIX/Linux
Partition information store
Partition table Partition table Disk label
Information about active partition Master Boot Record (MBR) Boot block Boot block
File Systems FAT16 , exFAT16 Macintosh Filing System (MFS) ufs
FAT32, FAT64 Hierarchical Filing System Extended Format (HFS+) extended file system (ext or ext fs)
NTFS Hierarchical Filing System (HFS) 13.
Clean installation is one where you move from the OS you are using to a new OS, whereas in upgrade installation you do not move completely, you keep the old settings and only change or upgrade certain parts of the OS and retain your files. You may need to clean install your OS after replacing the disk because your old OS may not be compatible with the new disk.
Release candidate (RC)- The last stage of software where the software is tested by vendors and users before the software released to be sold.
Release to manufacturing (RTM) version- At this stage the software has been tested and it is said to be ready to be sold to the market with all the new featues.
Alpha software stage- This is the development version of software in which there are likely to be problems, and not all of the functionalities are available.
Beta- After a software has passed the alpha stage it now comes to the beta stage where testing occurs and there may be thousands of people testing the software and it still has bugs at this stage but not as much as in alpha stage.
15. Before you upgrade your production computers, you need to test the new OS on a sample computer that is similar to the computers you are upgrading (production computers), in terms of the amount of memory, speed of the CPU etc.
Operating System Windows Vista or later Mac OS X or later Linux Fedora 13 or later
Backup Utility Backup and Restore Center Time Machine backup utility dump command
17. There is no back up path that goes directly from vista home basic edition to Windows 7 Enterprise edition, from vista Home basic edition you can only upgrade to Windows 7 Home basic, Home premium or ultimate editions. You would have to perform a clean installation.
18. MacBook pro can be upgraded from Mac OS sierra to Mac OS high Sierra. The required memory for Mac OS high Sierra is 2GB and the current Mac OS Sierra has 8GB of memory
Also the supported version is OS X 10.8 or later and mac OS sierra’s version is later than OS X10.8 (I.E 10.12.1)
Prints an object 3D printer
Large architectural drawings Plotter
Good quality photographs Ink-jet
Device Connection SATA USB3.0 Light Peak
Speed 6Gbps 4.8Gbps 10Gbps(expected to rise to 100Gbps)
Basic disk-refers to a disk (physical hard drive) that contains partitions, such as primary partitions and logical drives.
Dynamic disk-Disk that has been initialized for dynamic storage (uses dynamic volumes to manage data) and allows ability to create volumes that span multiple disks
Advantages of dynamic disk
Ability to create volumes that span multiple disks
Ability to create fault-tolerance volumes.
Dynamic disks offer greater flexibility for volume management because they use a database to track information about dynamic volumes on the disk and about other dynamic disks in the computer
Fault-tolerance –enables a system to continue operating properly in the event of the failure of some of its components.
Disk mirroring duplicates the contents of a disk on another disk, this helps in cases where the main disk fails then the second disk can now be used without losing data (even the data you recently created).
A normal PC serves many basic functions these machines are not powerful, Gaming PCs need to be powerful and access information fast without user having to wait for it to process information from the hard drive then displaying to the user.
Traditional disk drive uses a technique with a read/write head to move around and read information from the right location on a storage platter, but SSDs do not depend on moving parts or spinning disks. For this reason SSDs are much faster and would be preferred for gaming PCs.
SAN- Sends data between servers over fibre channel. Used to connect servers and storage devices directly without connecting to a main large network. The speed of fibre channel is 8Gbps typically.
NAS- Connects storage to a LAN.Connects server with storage over the main network rather than by a separate Fibre Channel connection. AS uses iSCSI for data transmission making the data transmission speeds to be associated with the actual speed of the network but faster than fibre channel speed.
Windows Disk Management tool-In Windows you get disk management for hard drives that allows you to create and delete partitions.
Disk Management Tools in UNIX/Linux-One of the utilities is sfdisk which allows you to view information about partitions, verify partitions and to repartition a disk.
Mac OS X Disk Utility-With the Mac OS X Disk you can partition, format, and manage hard drives as well as removable hard drives.
27. Analog modem takes the digital signal from the computer and modulates to analog signal and vice versa, the modulation and demodulation process is done by a component of the modem called the data pump, with the controller interpreting the commands. The UART handles data flow through a modem or a serial port.
28. Software based modem is one that has the controller functions implemented in software instead of hardware while retaining a data pump as hardware. Hardware based modem has controller hardware that interprets commands instead of a software handled by the PC.
Wireless DSL ISDN Satellite
Speed Type of network that carrier implements determines the speed. (14.4 Mbps download speed and up to 5.8 Mbps upload speed on a 3G network can be provided) Currently can get up to 8Mbps BRI) has an aggregate data rate of 144 Kbps.
(PRI)speed of to 1.544 Mbps 5.0 Mbps for download speeds and up to 300 Kbps for uploading data
But Speed depends on weather
Connection interface copper wire and fiber-optics copper wire and fiber-optics
standard copper telephone line pairs with digital equipment Wireless(to connect: Satellite dish
Digital, digital modem)
Security Implement or configure strong default password, turn on encryption, disable the Service Set Identifier (SSID) display Less likelihood that the signal can be trapped without the telco being alerted since its dedicated to one user. CHAP- station sends a challenge to the remote station, which replies with a value produced by applying a one way Hash function to the ‘challenge string’ and other specifics, as required, (password is not transmitted across the link). If this reply matches the station’s own hash calculation, authentication is acknowledged SATCOM-Traffic that is sent over satellite is encrypted using a key(group key)
30. Parity is either odd or even, if parity is set to even and we have odd number of 1’ns a parity bit (in this case a 1) can be added to verify the error in data transmission and vice versa.
31. Data compression can compress repetitive data into a single dot with a number indicating how many times the data is repeated. This reduces the amount of bandwidth used.
LAN- Covers a relatively small area (e.g. network in an office area)
WAN- Offers networking services over a long distance, such as between cities
Network topology—Physical design of the network
Bus topology-Straight-line design with network devices attached (has 2 end points with terminator on each end) in a straight line.
Star topology—Devices are connected like a circle to a central point (device).
Star-bus hybrid topology—Combination of star and hybrid topologies, with each bus design radiating out like a star and acting like a separate bus logical segment.
Ring topology- Computers are connected to one another in a ring shape (circle) with no terminators.
34. MAC address
35. Use of each in a network:
Switch- a switch can be used to connect multiple hosts (PCs) to the network but unlike a hub, a switch forwards a message to a specific host.
Router-Router is used to direct traffic in a network
Hub- Hub functions as the central connection point of a network. It joins together the workstations, printers, and servers on a network, so they can communicate with each other
Firewall- Used to control what traffic is allowed to traverse from one side to the other.
CSMA/CD is used by Ethernet. Computers and devices check the communication cables to see if there is a carrier signal present. If not present, the device begins to transmit its first frame. If another device has tried to send at the same time, collision will occur and the frames are discarded. Each device then waits a random amount of time and retries until successful in getting its transmission sent.
CSMA/CA is used in wireless connections. In CMSA/CA a wireless station that wants to transmit, listens for other transmissions before transmitting, if there is no transmission from other the station will begin transmitting.
Save money as you don’t have to buy the same resource again.
Easy to manage/configure or update network as there aren’t many similar resources.
Save space (working space) in building or work area.
User accounts-Give user access to servers and resources.
Account policies-Ensures that only authorized personnel can access accounts(e.g. Password policy)
Permissions (Access Privileges) – Permissions allow user to protect contents of files and folders so that they are accessed only by authorized people.
39. SAMBA/ SMB is a protocol –provides shared access to folders and printers
– Remote procedure calls (RPCs)-allows services and software on a computer to access and use services and software on a different computer.
In root directory you must not have many directories.
Keep OS files in the default directory that the vendor recommends.
Keep different software versions in their own directories
Group data files in directories based on their functions.
Home directories must match functions of the organization’s users
Files with similar security needs must be group in 1 directory
41. Disk Cleanup tool can be used in windows to delete unused files.
Types of files that can be deleted include:
Files (program files) you downloaded.
Offline web pages
Fragmentation means that unused space develops between files and other information written on a disk.
In a fragmented disk:
More space that is wasted.
The disk read/write head begins to work harder to find individual files and data in files resulting in disk performance suffering because it takes the read/write head longer to find information, and it takes longer to find an appropriately sized unused location on which to write information.
The second problem is that the read/write head works harder when there is more disk fragmentation, resulting in a possible hardware failure
Defragmentation must be done to correct it.
Linux-fsck and p-fsck
Mac OSX-Disk first aid
Disk stripping- process of dividing data into blocks and spreading the data blocks across multiple storage devices such as in RAID.
RAID uses disk stripping to extend the life of a set of disks.
Binary Differential Incremental File by file
Backs up disk files in binary format to create exact image of the disk contents Backs up all files which indicate that they need to be backed up( an archive attribute) but does not remove the archive attribute Backs up all with archive attribute which indicate that they need to be backed up but removes the archive attribute from each file after back up All files are backed up as individual directories and files