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Thread: Can anyone explain OS File system

  1. #1
    Junior Member
    Join Date
    Oct 2004

    Can anyone explain OS File system

    Hello all...

    I am new here and this is my first post...
    I would like to learn more about computers. To start with, what is a file system in an OS (like fat, NTFS,), I mean what are its functions.

    I would really appreciate if anyone could explain this to me or direct me to any website that explains this.....

    I am trying to learn more about computers from basics..... all help will be appreciated


  2. #2

  3. #3
    Join Date
    Feb 2004
    Filesystem is a file layout in your hard disk corresponding your operating system,I assume.There are quite a lot of file system. Are you doing courses on computer ?? I am assuming you are starting A+

  4. #4
    Senior Member gore's Avatar
    Join Date
    Oct 2002
    File systems depend on OS. DOS for example has FAT, which is File Allocation Table, which is just the way a computer stores and retrieves files on the HD, and some file systems, like EXT3 and Reiser, are ones that can keep a sort of "Log" which means if something makes the machine crash, you can start up a lot faster because it has a log / "Journal" of everything, which may add a slight bing on performance, but nothing you'll notice, as ReiserFS has proven too be very fast. If Reiser crashes on you, you can get back up very fast, it's like Viagra, you can get it up fast because it has a Journal of MetaDeta, so it knows what's going on.

    FFS is what Free BSD uses, which is the Berkeley "Fast File System" and it has a lot of very advanced features like soft updates and things like that too try and keep up with Linux, and maybe excel.

    I just crawled out of bed and haven't had my medication kick in yet so give me a while and I'll come edit all of this and add more in detail.

  5. #5
    Junior Member
    Join Date
    Oct 2004
    Thanks a bunch guys......

    Well....rajunpl.....m thinking of taking A+, was reading some materials online..... and was getting confused with some basic stuffs.....

    This might sound stupid.....since every thing is written in 1s & 0s on the harddisk....
    Why is it not possible to access an NTFS partition from a FAT partition....

  6. #6
    ********** |ceWriterguy
    Join Date
    Aug 2004
    Why is it not possible to access an NTFS partition from a FAT partition....
    It has to do with the os itself - NTFS is a completely different method of posting and getting files from secondary storage than FAT is. One cannot read the other because it can't interpret the data correctly. Windows tried to counteract this and has had some success, by building both NTFS and FAT command interpreters into XP, but the success was limited.
    Even a broken watch is correct twice a day.

    Which coder said that nobody could outcode Microsoft in their own OS? Write a bit and make a fortune!

  7. #7
    Senior Member
    Join Date
    Mar 2004

    One aspect is that the filesystem let you organise your files, eg you can
    create folders in folders, put files in them, add permissions etc. ("logical layer").

    A second aspect is the "physical layer": Eg it might indeed happen that the
    harddrive (as one example of a storage device) rotates faster than the
    head can write the data you want to - hence, your data ("0" and "1"s) is
    physically distributed all over the harddisk (or network (NFS)),
    called fragmentation. So in order to access your file, this particular
    information about the distribution of your file has to be stored in order to
    be able to put it together.

    A third aspect is consistency - ("stability layer"). Assume that our
    OS does not write data immediately to the harddisk etc. (caching) in order
    to enhance the performance. If you now turn of your computer, this caching
    produces inconsistencies in your filesystem - and this has to be recovered,
    if at all possible. There are two types of data:
    file-data (the data of the file itself) and meta-data (name of the file,
    info about the physical position of the "0" and "1"'s).

    You may have noticed, that this recovery takes horrendously long while
    using FAT/ext2, but is invisible while using NTFS/reiser/ext3. The keyword in
    this context is "journaling". A journal keeps track of the transactions to
    the disk. The check in the rebooting process after a power-loss can be
    processed very quickly: just check the journal whether all planned transactions
    were successful before otherwise provide a rollback!
    There are several levels: journaling of all data (ext3, more recent reiser-versions?,
    more recent NTFS?), which might result in no loss at all, journaling of meta data only
    (older reiser-versions, older NTFS-versions), with fast recovery, but newer file data
    are definitively lost), nothing at all(FAT, ext2).

    Some information here might be a bit old. I apologize for any inaccuracy.

    A remark to your question about FAT/NTFS: Since filesystems are, simplified,
    just a "view" on your physical data, you can <I>convert</I> one view into the other
    (with loosing some specifiic "logical" information (permission etc.)).
    But you cannot read a NTFS partition using a FAT-only OS (boot up with MSDOS 3.1 or so ),
    simply because FAT is another view. You cannot a priori look at a sequence of
    bytes in your memory, and immediately recognise what it represents.

    If the only tool you have is a hammer, you tend to see every problem as a nail.
    (Abraham Maslow, Psychologist, 1908-70)

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