Reliable Vfat (or any reliable windows filesystem in linux) - Linux

This is a discussion on Reliable Vfat (or any reliable windows filesystem in linux) - Linux ; Hii I am facing some strange problem relating to Vfat filesystem in linux.I have one embedded device with journaling yaff2 partition as root partition. We have a slot for SD memory disk which is formatted as vfat filesystem.Because that has ...

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Thread: Reliable Vfat (or any reliable windows filesystem in linux)

  1. Reliable Vfat (or any reliable windows filesystem in linux)

    Hii
    I am facing some strange problem relating to Vfat filesystem in
    linux.I have one embedded device with journaling yaff2 partition as
    root partition. We have a slot for SD memory disk which is formatted
    as vfat filesystem.Because that has to be recognized in windows.Since
    Vfat is not journalled , its not at all reliable. If I remove that SD
    card in the middle of some copy process to SDcard, it just corrupt its
    superblock and might cause considerable damage to superblock.

    My aim is now to make superblock noncorrupt also I cant use any
    journalling linux filesystem as it cant be recognized in windows.

    How to make Vfat filesystem stable or fault tolerant? I tried to find
    whether any journalled version of vfat available.I couldnt find any


    Any suggestion please

  2. Re: Reliable Vfat (or any reliable windows filesystem in linux)

    "GrPrd" writes:

    > Hii
    > I am facing some strange problem relating to Vfat filesystem in
    > linux.I have one embedded device with journaling yaff2 partition as
    > root partition. We have a slot for SD memory disk which is formatted
    > as vfat filesystem.Because that has to be recognized in windows.Since
    > Vfat is not journalled , its not at all reliable. If I remove that SD
    > card in the middle of some copy process to SDcard, it just corrupt its
    > superblock and might cause considerable damage to superblock.
    >
    > My aim is now to make superblock noncorrupt also I cant use any
    > journalling linux filesystem as it cant be recognized in windows.
    >
    > How to make Vfat filesystem stable or fault tolerant?


    You can't. The closest you can get is by mounting with the sync
    option, but you probably don't want to do that with flash media.

    There are Windows drivers supporting ext3 and other filesystems. If
    you have control over the machines that need to read this SD card,
    this may be an option.

    --
    Mns Rullgrd
    mans@mansr.com

  3. Re: Reliable Vfat (or any reliable windows filesystem in linux)

    Thanks for the information

    But I wanna know whether I can add some kind of journaling
    functionality to Vfat? As we already have vfat source code as part of
    linux kernel package.

    Log every operation on metadata(on superblock) . Whenever card is
    taken out in the middle of some operation , and put back after some
    time , recovery daemon should run to check the consistency and repair
    it from logged operation.

    Can it be possible?

  4. Re: Reliable Vfat (or any reliable windows filesystem in linux)

    GrPrd wrote:
    > If I remove that SD card in the middle of some copy process to SDcard, it
    > just corrupt its> superblock


    > Any suggestion please


    Yeah, don't pull out the card in the middle of a copy process.

    Does your embedded device have some sort of display, light or beeper
    that could be used to tell the operator that it is safe to remove the
    card?

    I use vfat on memory sticks, and some devices here, and I have been
    using vfat filesystems on many devices up and till a few years ago. I
    have had no real problems with vfat, except as you have, when a device
    is removed during filesystem access, but I am careful not to do this.

    > My aim is now to make superblock noncorrupt also I cant use any
    > journalling linux filesystem as it cant be recognized in windows.


    The superblock is not usually a problem, this can usually be copied
    onto a spare sector, and restored if corruption is found.

    The problem with removing during disk access is that the partition
    tables that follow the superblock get damaged.

    You could format the devices as ext3 and install an ext3 driver on the
    Microsoft Windows based machines.

    I don't know how reliable this is. I would still prefer not to remove
    the card during filesystem access, if this could be determined.

    Regards,

    Mark.

    --
    Mark Hobley,
    393 Quinton Road West,
    Quinton, BIRMINGHAM.
    B32 1QE.

  5. Re: Reliable Vfat (or any reliable windows filesystem in linux)

    GrPrd wrote:

    > But I wanna know whether I can add some kind of journaling
    > functionality to Vfat? As we already have vfat source code as part of
    > linux kernel package.


    You could do this, but this is not going to help you, if your card is
    next plugged into the Microsoft Windows machine, unless you can also
    write a compatibility mode driver for that platform.

    This is not difficult on Windows '98 and below (as long as you know
    MSDOS, assembly language and are ok with writing memory resident code
    and interrupt handlers), because you can load your drivers prior to
    starting the Microsoft Windows kernel. The operating system detects
    that the driver is not flagged as "safe", and runs the device in
    compatibility mode through the memory resident interrupt driver.

    I don't know how Microsoft Windows XP handles compatability mode. I have
    not tried this on XP, and there is a big lack of documentation on Microsoft
    Windows internals. I certainly have never seen any technical reference
    manual.

    Regards,

    Mark.

    --
    Mark Hobley,
    393 Quinton Road West,
    Quinton, BIRMINGHAM.
    B32 1QE.

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