Expert answer:Operating Systems
Expert answer:Task:1 Submit a work proposal for this assignment within 24 Hours which must include: 1) Understanding of deliverables – a detail description of deliverables 2) General overview and initial understanding of solution. Task:2 AT&T being the largest telecommunication service provider in USA they had noticed a potential growth in the field of telecommunication and wanted to start its operation in sultanate of Oman. You are being hired to evaluate the concerned raised by their CEO. Your task is to find out a solution of an Operating System for whole company that is feasible for their smooth operations in the country. The concerns are given below: 1) There should be an automated system for deadlock detection and recovery. 2) Memory management in terms of paging. 3) Storage techniques used if the company wants to sustain the infrastructure for 05 years. 4) Security and protection for their users and employees. Task:3 Your mission is to decide which OS the company should choose and why. You have to convince the CEO regarding his concerns and device a solution based on the research paper and other relevant articles with proper justification.You can read the article “ Modeling the Evolution of Operating Systems: An Empirical Study” which highlights the key aspects needed to consider while developing and deploying OS and other relevant articles provided to you as Before-Class Activities. a. Description of Proper Process Management to avoid Deadlock.b. Explanation of Memory Management; Paging Implementation.c. Storage Techniques. d. Security and Protection Mechanism.** Total No. of pages: 10 Pages.** At least 10 References using CU Harvard Style. ** Citations is Required. ** Provide Suitable Diagrams with Explanation for Task – 2. ** Submit the Work Proposal within 24 Hours.
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DEPARTMENT OF COMPUTING
OPERATING SYSTEMS
INDIVIDUAL ASSIGNMENT
COMP 20004
SPRING – 2016
SESSION – C
STUDENT NAME: Hamad Tareq Al Malki
STUDENT ID: 12F9233
1
Table of Contents
Cover page ………………………………………………………………………………………………………………………1
Table of content ……………………………………………………………………………………………………………….2
Introduction ……………………………………………………………………………………………………………………..3
Deadlock …………………………………………………………………………………………………………………….. 3-4
Memory management …………………………………………………………………………………………………… 4-5
Storage Techniques ………………………………………………………………………………………………………. 6-7
Security and Protection ……………………………………………………………………………………………………..7
References ……………………………………………………………………………………………………………………….8
2
INTRODUCTION
Linux is a UNIX based operating system is open source software created and developed by
LINUS TORVALDS on 1991. He began a project that became later the Linux kernel. It doesn’t
belong to nobody and free to download and use. You can customize your own operating system
for free and as a result it developed into a powerful operating system that is gaining the
popularity worldwide.
DEADLOCK:
Deadlock can happen whenever multiple processes interact. It happens in the operating system
when two processes needs each other resources and are waiting, this is called deadlock. For
example there are four cars in a four way signal road and each one of them is waiting for the
other to pass, this is a deadlock situation. On Early times, operating systems ran only one
program at a time and all the resources of the system are available to the running program. Later
on operating systems started executing multiple programs at once and some operating systems
started offering dynamic resources allocation, and that started the deadlock situation in any
operating system
WAIT – FOR – GRAPH is an algorithm used to detect deadlock situation, it is used when the
resources have only one instances. The following figure is without the resources because all
contain one only and it shows how WFG detect deadlock:
3
In Linux operating system there is a utility used for static deadlock detection which is lockdep.
When an algorithm detect that a deadlock exist, it can informs the operator that deadlock has
been occurred so he deal with it manually, or let the system recover from it automatically. There
are two ways for breaking a deadlock, the simply way is to abort one or more processes to break
the waiting circuit, and the other way is to preempt resources from the deadlocked processes.
The other strategy is described by ostrich algorithm which is to ignore the problem, the kernel
lock up and reboot, also device driver lock up, and remove the device and then restart it.
(Anon., 2004)
Deadlock can be avoided by taking care of the resources scheduling. For each resource request
the system see if providing the request will enter the system in an unsafe state, meaning this state
could enter the system in deadlock situation. The system then only provide requests that lead to
safe state and in order the system to figure out if the next request will enter it in a safe or unsafe
state, all resources that are available, requested and number of resources. The most used
algorithm to avoid deadlock is banker’s algorithm.
MEMORY MANAGEMENT:
Virtual memory is a very powerful aspect of memory management in Linux kernel, virtual
memory make your system looks like it has more than one memory. Virtual memory is memory
addresses that maps to physical addresses, when a program instruction is executed it read the
instruction from the virtual memory, but before reading the instruction it converts the memory
addresses to physical addresses. Memory addresses converted to physical addresses are done
based on the information in the page table that is maintained by the operating system. The virtual
memory and the physical memory division into fixed sized blocks are known as pages. The
virtual address is usually divided into two parts: offset and virtual page frame number.
Whenever a processor encounter a virtual address, it evolve the virtual page frame number from
it and convert it to physical page frame number and the offset help it to get the exact address of
the physical page, all of this is done in the page tables.
4
Paging is an important part of the virtual memory implementation, paging allow physical
addresses of a process space to be non-contiguous. The usual size of page or frame is 4 KB. Any
time a free frame is available in the main memory the physical page of the process can be loaded
into it and the page table will take care of the logical address mapping.
Swapping is a method of copying the entities address space from the main memory to some
secondary memory storage; it is usually done by CPU Scheduling. In the operating system
Read-to-run queue contains the information of the processes that are ready to be executed, the
images of the processes can be on the disk or the memory, and if the next process in execution is
on the disk there is no space in the memory. The process that is resident in the memory is
swapped with the process in the disk to allocate space to its data and text segment.
Demanding paging is a technique used in implementing virtual memory, here also the process
allocated memory is in term of pages. A page that is in the memory and a part of the process
address space is replaced with another page that belong to the process on the disk.
5
STORAGE TECHNIQUES:
The Linux file system hierarchy standard is the standard way of organizing user logs, files,
utilities, program, kernels, and more categories. Also it is the Linux foundation, Linux supports
wide range of file systems but the common choices are Ext family (ext2, ext3, and ext4), JFS,
ReiserFS, BTRFS, and XFS. An important thing to mention is that Linux deal with everything as
a file, this means the directory is a file, and text file is a file and so on. There are several
directories associated with Unix/Linux operating system. This directories can organize the user
logs, kernels, files, program, utility, drivers, and more categories. The standardization of
Filesystem hierarchy standard made it easy for users to of UNIX operating systems to use Linux
operating system. Every Filesystem hierarchy standard starts with root directory also known as
slash (/) and all directories shown in the table are the subdirectories of main root directory unless
they’re mounted separately. The subdirectories files can be found in the same exact partition of
the main root directory. Bellow figure shows some linux commands:
6
(Anon., 2013)You need to be aware that Linux has different type of file system not like windows
having two only. Linux has regular files, links, fifos, and Sockets. Regular files are similar to any
operating system files which are executing files or text files, or etc. the file type links is a pointer
that links to files in the file system. The file type fifo also known as first input first output are a
kind of special files which meanly the first file to be in the first file to be out, the data moves in
one direction only in the fifo. While the sockets are same as FIFO that transfer information
between sockets only. This type of files can move data bi-directionally not like the FIFO.
SECURITY AND PROTECTION:
The key advantages of Linux security are in the account privilege. Users in Linux are not usually
given administrator access by default like users in windows; rather they are given lower-level
accounts. That means when a virus attacks it won’t have the root access to do some serious
damage. Just the local user files and programs would be affected. That makes a major difference
in a huge business corporate. Viruses and worms cannot spread fast in Linux operating systems
because Linux user would read the email, then save the attachment, and permit it execution and
run the execution. It’s not very likely a Linux user might do all these steps.
In Linux operating system each newly created isn’t executable by default under Linux and the
user need to make this file by explicit action. Linux users don’t necessary need anti-virus
because in Linux a user has very limited permissions. To perform administrative tasks he should
give his password and he will have 15 minutes of root authority only.
(Noyes, 2010)In terms of vulnerabilities Linux operating systems checks for security updates
daily, it is important to install the recommended update at once if you want your system to be
secure as possible. The best protection against anything is by installing a well-supported Linux
operating system like Ubuntu and Linux Mint and check for daily updates. The most important
point is to install software’s only from the official software website. Firewalls are already in
Linux by default named as IPtables. It can be managed through an application called uncomplicated firewall which is installed by default.
7
REFERENCES:
Works Cited
Anon., 2004. CS 551: Distributed Operating Systems. [Online] (2) Available at:
http://www.cs.colostate.edu/~cs551/CourseNotes/Deadlock/WFGs.html [Accessed 2 June 2016].
Anon., 2013. Linux file system and directory structure. [Online] Available at:
http://computernetworkingnotes.com/linux-file-system-basic-commands/linux-filesystems.html
[Accessed 4 June 2016].
Noyes, K., 2010. Why Linux Is More Secure Than Windows. [Online] Available at:
http://www.pcworld.com/article/202452/why_linux_is_more_secure_than_windows.html [Accessed 4
June 2016].
8
INTRODUCTION
Linux is a UNIX based operating system is open source software created and developed by
LINUS TORVALDS on 1991. He began a project that became later the Linux kernel. It doesn’t
belong to nobody and free to download and use. You can customize your own operating system
for free and as a result it developed into a powerful operating system that is gaining the
popularity worldwide.
DEADLOCK:
Deadlock can happen whenever multiple processes interact. It happens in the operating system
when two processes needs each other resources and are waiting, this is called deadlock. For
example there are four cars in a four way signal road and each one of them is waiting for the
other to pass, this is a deadlock situation. On Early times, operating systems ran only one
program at a time and all the resources of the system are available to the running program. Later
on operating systems started executing multiple programs at once and some operating systems
started offering dynamic resources allocation, and that started the deadlock situation in any
operating system
WAIT – FOR – GRAPH is an algorithm used to detect deadlock situation, it is used when the
resources have only one instances. The following figure is without the resources because all
contain one only and it shows how WFG detect deadlock:
1
In Linux operating system there is a utility used for static deadlock detection which is lockdep.
When an algorithm detect that a deadlock exist, it can informs the operator that deadlock has
been occurred so he deal with it manually, or let the system recover from it automatically. There
are two ways for breaking a deadlock, the simply way is to abort one or more processes to break
the waiting circuit, and the other way is to preempt resources from the deadlocked processes.
The other strategy is described by ostrich algorithm which is to ignore the problem, the kernel
lock up and reboot, also device driver lock up, and remove the device and then restart it.
(Anon., 2004)
Deadlock can be avoided by taking care of the resources scheduling. For each resource request
the system see if providing the request will enter the system in an unsafe state, meaning this state
could enter the system in deadlock situation. The system then only provide requests that lead to
safe state and in order the system to figure out if the next request will enter it in a safe or unsafe
state, all resources that are available, requested and number of resources. The most used
algorithm to avoid deadlock is banker’s algorithm.
MEMORY MANAGEMENT:
Virtual memory is a very powerful aspect of memory management in Linux kernel, virtual
memory make your system looks like it has more than one memory. Virtual memory is memory
addresses that maps to physical addresses, when a program instruction is executed it read the
instruction from the virtual memory, but before reading the instruction it converts the memory
addresses to physical addresses. Memory addresses converted to physical addresses are done
based on the information in the page table that is maintained by the operating system. The virtual
memory and the physical memory division into fixed sized blocks are known as pages. The
virtual address is usually divided into two parts: offset and virtual page frame number.
Whenever a processor encounter a virtual address, it evolve the virtual page frame number from
it and convert it to physical page frame number and the offset help it to get the exact address of
the
physical
page,
all
of
this
is
done
in
the
page
tables.
2
Paging is an important part of the virtual memory implementation, paging allow physical
addresses of a process space to be non-contiguous. The usual size of page or frame is 4 KB. Any
time a free frame is available in the main memory the physical page of the process can be loaded
into it and the page table will take care of the logical address mapping.
Swapping is a method of copying the entities address space from the main memory to some
secondary memory storage; it is usually done by CPU Scheduling. In the operating system
Read-to-run queue contains the information of the processes that are ready to be executed, the
images of the processes can be on the disk or the memory, and if the next process in execution is
on the disk there is no space in the memory. The process that is resident in the memory is
swapped with the process in the disk to allocate space to its data and text segment.
Demanding paging is a technique used in implementing virtual memory, here also the process
allocated memory is in term of pages. A page that is in the memory and a part of the process
address space is replaced with another page that belong to the process on the disk.
3
STORAGE TECHNIQUES:
The Linux file system hierarchy standard is the standard way of organizing user logs, files,
utilities, program, kernels, and more categories. Also it is the Linux foundation, Linux supports
wide range of file systems but the common choices are Ext family (ext2, ext3, and ext4), JFS,
ReiserFS, BTRFS, and XFS. An important thing to mention is that Linux deal with everything as
a file, this means the directory is a file, and text file is a file and so on. There are several
directories associated with Unix/Linux operating system. This directories can organize the user
logs, kernels, files, program, utility, drivers, and more categories. The standardization of
Filesystem hierarchy standard made it easy for users to of UNIX operating systems to use Linux
operating system. Every Filesystem hierarchy standard starts with root directory also known as
slash (/) and all directories shown in the table are the subdirectories of main root directory unless
they’re mounted separately. The subdirectories files can be found in the same exact partition of
the main root directory. Bellow figure shows some linux commands:
4
(Anon., 2013)You need to be aware that Linux has different type of file system not like windows
having two only. Linux has regular files, links, fifos, and Sockets. Regular files are similar to any
operating system files which are executing files or text files, or etc. the file type links is a pointer
that links to files in the file system. The file type fifo also known as first input first output are a
kind of special files which meanly the first file to be in the first file to be out, the data moves in
one direction only in the fifo. While the sockets are same as FIFO that transfer information
between sockets only. This type of files can move data bi-directionally not like the FIFO.
SECURITY AND PROTECTION:
The key advantages of Linux security are in the account privilege. Users in Linux are not usually
given administrator access by default like users in windows; rather they are given lower-level
accounts. That means when a virus attacks it won’t have the root access to do some serious
damage. Just the local user files and programs would be affected. That makes a major difference
in a huge business corporate. Viruses and worms cannot spread fast in Linux operating systems
because Linux user would read the email, then save the attachment, and permit it execution and
run the execution. It’s not very likely a Linux user might do all these steps.
In Linux operating system each newly created isn’t executable by default under Linux and the
user need to make this file by explicit action. Linux users don’t necessary need anti-virus
because in Linux a user has very limited permissions. To perform administrative tasks he should
give his password and he will have 15 minutes of root authority only.
(Noyes, 2010)In terms of vulnerabilities Linux operating systems checks for security updates
daily, it is important to install the recommended update at once if you want your system to be
secure as possible. The best protection against anything is by installing a well-supported Linux
operating system like Ubuntu and Linux Mint and check for daily updates. The most important
point is to install software’s only from the official software website. Firewalls are already in
Linux by default named as IPtables. It can be managed through an application called uncomplicated
firewall
which
is
installed
by
default.
5
REFERENCES:
Works Cited
Anon., 2004. CS 551: Distributed Operating Systems. [Online] (2) Available at:
http://www.cs.colostate.edu/~cs551/CourseNotes/Deadlock/WFGs.html [Accessed 2 June 2016].
Anon., 2013. Linux file system and directory structure. [Online] Available at:
http://computernetworkingnotes.com/linux-file-system-basic-commands/linux-filesystems.html
[Accessed 4 June 2016].
Noyes, K., 2010. Why Linux Is More Secure Than Windows. [Online] Available at:
http://www.pcworld.com/article/202452/why_linux_is_more_secure_than_windows.html [Accessed 4
June 2016].
6
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