[svlug] I thought that too, *BUT* ... -- RE: 2GB file size limit ... kernels 2.2.14-6.1.1 / 2.2.14-12

kmself@ix.netcom.com kmself at ix.netcom.com
Mon May 22 16:57:43 PDT 2000

On Mon, May 22, 2000 at 05:13:49PM -0400, Bryan -TheBS- Smith wrote:
> I thought that too, *BUT* ... -- RE: 2GB file size limit ... kernels 2.2.14-6.1.1 / 2.2.14-12
> On Mon, 22 May 2000, Robert Hajime Lanning wrote:
> > I would thing the file size limit is based on the filesystem used
> > which (of course) must be supported by the kernel.  You need the inodes
> > to support a filesize larger than a unsigned 32 bit value.  (hence the
> > 64bit filesystems)
> Actually, I though that too ... *BUT* there *IS* a patch to support
> >2GB files on Ext2 partitions.  It is now part of the 2.3.x series.
>  I too thought it was impossible until I saw it in the change logs.
>  Maybe Ext2 *DOES* allow for 64-bit file sizes (but the
> unpatched kernel only uses 32-bit values for computations)?!?!?!
> Maybe it is just a patch to support upto 4GB files?  I don't know. 
> That would support my 2.5GB file.  But once I upgraded to
> 2.2.14-12, I was stuck at the 2GB limit again.
> Anyone know any more info???
> And I know this isn't "proof" or anything, but here's that file on
> an Ext2 partition (from when I was running 2.2.14-6.1.1):
> rw-r-----   1 ryan     staff    2593838749 May 20 20:50 oldpcshares.tgz
> Our attempt to re-copy it under 2.2.14-12 failed a second time.

I can only add some hearsay to the conversation.

Talking with Hans Reieser, Ted T'so, and Alan Cox a couple of years
back, the suggestion was made to utilize some value between 32 and 64
to hold filesize information on 32 bit systems.  The problem being,
IIRC, that going full 64 bit had significant impacts on VFS -- the
virtual filesystem -- which essentially affects all *memory* operations.
Not good for the 99.9+% of the population who doesn't need 2GB support.

The upshot seemed to be that a value not terribly much larger than 32
would still provide a significantly large filesize limit.  40 or 42
bytes, say, would be on the order of 10 - 44 TB.  Good enough for
government work.  This was thought by those who know to be a potentially
reasonable compromise.

That's what I know.

Karsten M. Self <kmself at ix.netcom.com>         http://www.netcom.com/~kmself
  What part of "Gestalt" don't you understand?       Debian GNU/Linux rocks!
    http://gestalt-system.sourceforge.net/    Rusty? http://www.kuro5hin.org
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