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    SubjectJournaling pointless with today's hard disks?
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    In the German computer community, a statement from IBM[1] is
    circulating which describes a rather peculiar behavior of certain IBM
    IDE hard drivers (the DTLA series):

    When the drive is powered down during a write operation, the sector
    which was being written has got an incorrect checksum stored on disk.
    So far, so good---but if the sector is read later, the drive returns a
    *permanent*, *hard* error, which can only be removed by a low-level
    format (IBM provides a tool for it). The drive does not automatically
    map out such sectors.

    IBM claims this isn't a firmware error, but thinks that this explains
    the failures frequently observed with DTLA drivers (which might
    reflect reality or not, I don't know, but that's not the point
    anyway).

    Now my question: Obviously, journaling file systems do not work
    correctly on drivers with such behavior. In contrast, a vital data
    structure is frequently written to (the journal), so such file systems
    *increase* the probability of complete failure (with a bad sector in
    the journal, the file system is probably unusable; for non-journaling
    file systems, only a part of the data becomes unavailable). Is the
    DTLA hard disk behavior regarding aborted writes more common among
    contemporary hard drives? Wouldn't this make journaling pretty
    pointless?


    1. http://www.cooling-solutions.de/dtla-faq (German)

    --
    Florian Weimer Florian.Weimer@RUS.Uni-Stuttgart.DE
    University of Stuttgart http://cert.uni-stuttgart.de/
    RUS-CERT +49-711-685-5973/fax +49-711-685-5898
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