Messages in this thread | | | Date | Tue, 22 Nov 2005 09:50:47 -0500 | From | Theodore Ts'o <> | Subject | Re: what is our answer to ZFS? |
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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....
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