On 25 Jul 02 at 7:44, Alexander Viro wrote:
> On Wed, 24 Jul 2002, Linus Torvalds wrote:
>
> > Note that there is one place where 64 bits is simply _too_ expensive, and
> > that's the page cache. In particular, the "index" in "struct page". We
> > want to make "struct page" _smaller_, not larger.
> >
> > Right now that means that 16TB really is a hard limit for at least some
> > device access on a 32-bit machine with a 4kB page-size (yes, you could
> > make a filesystem that is bigger, but you very fundamentally cannot make
> > individual files larger than 16TB).
>
> ITYM "8Tb" - indices are signed, IIRC. OTOH, it's not 2^31 * PAGE_SIZE -
> it's 2^31 * PAGE_CACHE_SIZE, which can be bigger.
>
> Al, still thinking that anybody who does mkfs.<whatever> on a multi-Tb
> device should seek professional help of the kind they don't give on l-k...
Don't worry. Netware (NW6) uses also 32bit for indices to page cache,
and 4KB page cache size, but in addition to our implementation they
(1) do not verify that file you created is smaller than 16TB, and
(2) they have signedness bug somewhere too. So if you'll create file
larger than 8TB, data you wrote in are silently discarded, while
file size is preserved.
I was really surprised when I updated ncpfs to access files > 4GB.
Written data were disappearing after server reboot :-(
Just my two cents.
Petr Vandrovec
vandrove@vc.cvut.cz
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This archive was generated by hypermail 2b29 : Tue Jul 30 2002 - 14:00:19 EST