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SubjectRe: BIG files & file systems
On Wed, Jul 31, 2002 at 08:26:38PM +0100, Christoph Hellwig wrote:
> On Wed, Jul 31, 2002 at 01:16:20PM -0600, Peter J. Braam wrote:
> > Hi,
> >
> > I've just been told that some "limitations" of the following kind will
> > remain:
> >
> > page index = unsigned long
> > ino_t = unsigned long
> >
> > Lustre has definitely been asked to support much larger files than
> > 16TB. Also file systems with a trillion files have been requested by
> > one of our supporters (you don't want to know who, besides I've no
> > idea how many bits go in a trillion, but it's more than 32).
>
> What about using 64bit machines? ..

It depends on many things:
- Block layer (unsigned long)
- Page indexes (unsigned long)
- Filesystem format dependent limits
- EXT2/EXT3: u32_t FILESYSTEM block index, presuming the EXT2/EXT3
is supported only up to 4 kB block sizes, that gives
you a very hard limit.. of 16 terabytes (16 * "10^12")
- ReiserFS: u32_t block indexes presently, u64_t in future;
block size ranges ? Max size is limited by the
maximum supported file size, likely 2^63, which is
roughly 8 * "10^18", or circa 500 000 times larger
than EXT2/EXT3 format maximum.
- ClusterFS: (Braam et.al.): 64 bit block indexes ?
System file size limitation, same as with ReiserFS.

(Just to illustriate a few..)


/Matti Aarnio
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