• [^] # Re: La journalisation n'a rien à voir avec la récupération de données pe

    Posté par . En réponse à la dépêche Ext4 bientôt sur votre bureau. Évalué à 2.

    > Cela arrive quand même très souvent avec les FS qui se disent journalisés actuels,

    Ils journalisent quoi ?

    Ext3 :
    Data Mode
    ---------
    There are 3 different data modes:

    * writeback mode
    In data=writeback mode, ext3 does not journal data at all. This mode provides
    a similar level of journaling as that of XFS, JFS, and ReiserFS in its default
    mode - metadata journaling. A crash+recovery can cause incorrect data to
    appear in files which were written shortly before the crash. This mode will
    typically provide the best ext3 performance.

    * ordered mode
    In data=ordered mode, ext3 only officially journals metadata, but it logically
    groups metadata and data blocks into a single unit called a transaction. When
    it's time to write the new metadata out to disk, the associated data blocks
    are written first. In general, this mode performs slightly slower than
    writeback but significantly faster than journal mode.

    * journal mode
    data=journal mode provides full data and metadata journaling. All new data is
    written to the journal first, and then to its final location.
    In the event of a crash, the journal can be replayed, bringing both data and
    metadata into a consistent state. This mode is the slowest except when data
    needs to be read from and written to disk at the same time where it
    outperforms all others modes.


    La majorité des fs journalisé font "data=writeback".
    Par défaut ext3 fait "data=ordered".

    > Les utilisateurs qui ont l'habitude de patcher leur noyau, d'utiliser des drivers graphiques buggy...

    Pour ça il n'y a que les backups.