Operating System - Chap. 8

Research Topic:

A. Research the size of operating system software by finding the amount of secondary storage (disk) space required by different versions of the same operating system or different operating systems. if their sizes are substantially different, explain why that may be the case, such as platform issues, features, etc. Cite your sources.

            Win 3.1 ~15MB, although it requires at least MS-DOS 6.22 to boot, so tack on another few megs.
            Win 95 b ~80MB
            Win 98 SE ~300MB
            Win 2000 Pro ~720MB with no service packs. After SP4, it's around 1GB.
            Win XP Pro, ~1.2GB with SP2.
            Suse 9.2
            Slackware 10.1
            Ubuntu
            Linspire 4.5
            Mandriva 10.1

http://www.overclockers.com/forums/showthread.php?t=397609

B. Consult current literature to research file-naming conventions for four different operating systems(not including UNIX,MS-DOS,Windows,or Linux). Note the acceptable range of characters, maximum length  case sensitive,etc.Give examples of both acceptable and unacceptable file names  for extra credit,explain how the file manager for those operating systems shorten long file names(if they do so) in their internal lists to make them easier to manipulate. Cite your sources.

             Mac 
Mac OS X allows you to name your files with up to 255 characters, including spaces and punctuation. The only illegal character for file and folder names in Mac OS X is the colon “:” and in some applications slashes (/) in naming a file. File names cannot start with a dot ".".

         In the Windows API (with some exceptions discussed in the following paragraphs), the maximum length for a path isMAX_PATH, which is defined as 260 characters. A local path is structured in the following order: drive letter, colon, backslash, name components separated by backslashes, and a terminating null character.  

           Ext4 filename length is 256 bytes and the allowable characters in directory entries are any byte except nul.

           Os4000 filename length is 8 bytes and the allowable characters in directory entries are A-Z and 0-9 with period as directory separator.

http://newitsc1405.blogspot.com/2011/10/chapter-8-file-naming-conventions.html
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
http://en.wikipedia.org/wiki/Comparison_of_file_systems

Exercises

1. Explain in your own words why the file deallocation is important and what would happen if it did not occur on a regular basis.

            = File deallocation is important because this process performed by the computer, releases the block of information from memory and allows that information to be used by a different program. If it does not occur in regular basis, or may had insufficient progress,  you have a memory leak(memory that was allocated, but never deallocated), and therefore can't be used by your program in the future, and may not be available for redistribution to other sources.

2. Describe how the File Manager allocates a file to a single user. List the steps that you think would be followed and explain your reasoning.

             = The File Manager handles all files on secondary storage media. To perform these tasks, file management must:
              -Identify the numerous files by giving unique names to them
              -Maintain a list telling where exactly each file is stored, how many sectors on 
                the medium it
              -Occupies, and in which order those sectors make up the file
              -Provide simple and fast algorithms to read and write files in cooperation                with the device manager
              -Give and deny access rights on files to users and programs
              -Allocate and deallocate files to processes in cooperation with the process manager
              -Provide users and programs with simple commands for file handling

3. Is device independence important to the File Manager? Why or why not? Describe the consequences if that were not the case.
           
             = Device Independence is important to the File Manager because it processes making a software application be able to function on a wide variety of devices regardless of the local hardware on which the software is used

4. Do you think that file retrieval is different on a menu-driven system and command driven-system? Explain your answer and describe any differences between the two. Give an example of when each would be preferred over the other.

           = All these processes were the same such that they do not automatically eradicate a file but prompt for the user's confirmation. But they also differ and matters on how fast and easier the user could take a request. 

                 

5. Imagine one real-life example of each: a multi-file volume and multi-volume file. Include a description of the media used for storage and a general description of the data in the file.

              = One real-life example of Multi-file volume is texting when you are going to send your message to more than two recipients because it contains many files in a single file which is compressed to a smaller size. One example of multi-volume file is a more than one CD for a product.The first example splits a large product distribution of a theoretical 2.1GB into 1 root installer and 3 more installers of 700 MB each (to fit on 700 MB compact disks. The second example is one installer which copies files from multiple disks onto the users' hard drive.

6. As described in this chapter, files can be formatted with fixed-length fields or variable field lengths. In your opinion, would be feasible to combine both formats in a single disk? Explain the reasons for your answer.

             = Yes, that can be done.You would just create your partitions and format them with your file system of choice.

7. Explain why it's difficult to support direct access to files with variable-length records. Suggest a method for handling this type of file direct access is required.

            = It is difficult because you have to use a different structure for each variable record 
               type.
So you need to be able to either identify the record type or there is an int which is the length of an array which is the last part of the struct.
You have to find a way that works for your file layout.

8. Give an example of the names of three files from your own computer that do not reside at the root or master directory. For each file, list both the relative filename and its complete filename.

                = exe - 1701_Gold_Trn_P.exe
                = ttf - Dovah.ttf
                = pdf - 1701AD_GOLD_Manual.pdf