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    SubjectRe: what is our answer to ZFS?
    On Tue, Nov 22, 2005 at 07:51:48AM +0000, Christoph Hellwig wrote:
    >
    > What is a '128 bit' or '64 bit' filesystem anyway? This description doesn't
    > make any sense, as there are many different things that can be
    > addresses in filesystems, and those can be addressed in different ways.
    > I guess from the marketing documents that they do 128 bit _byte_ addressing
    > for diskspace. All the interesting Linux filesystems do _block_ addressing
    > though, and 64bits addressing large enough blocks is quite huge.
    > 128bit inodes again is something could couldn't easily implement, it would
    > mean a non-scalar ino_t type which guarantees to break userspace. 128
    > i_size? Again that would totally break userspace because it expects off_t
    > to be a scalar, so every single file must fit into 64bit _byte_ addressing.
    > If the surrounding enviroment changes (e.g. we get a 128bit scalar type
    > on 64bit architectures) that could change pretty easily, similarly to how
    > ext2 got a 64bit i_size during the 2.3.x LFS work.

    I will note though that there are people who are asking for 64-bit
    inode numbers on 32-bit platforms, since 2**32 inodes are not enough
    for certain distributed/clustered filesystems. And this is something
    we don't yet support today, and probably will need to think about much
    sooner than 128-bit filesystems....


    - Ted
    -
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