[NTLUG:Discuss] 2GB+ file sizes

[Jeff Rush]

Yes, the filesystems themselves under Linux are 64-bit offset clean
and don't have the 4GB limit.  The limit comes from the C API
that uses C longs (32-bit values) to provide seeking/file size info.
Without breaking a lot of apps by using two C longs to make a
value, there is little to do until the 64-bit CPUs and C longs become
64-bit values.  This messiness is present in any C runtime that
maps longs to 32-bits.

There are sometimes OEM-specific APIs to get around it but
I presume you're talking about standard Linux applications using
files > 4GB.

-Jeff Rush


On Thu, 21 Oct 1999 23:18:56 -0500, cbbrowne at godel.brownes.org wrote:

>On Thu, 21 Oct 1999 17:06:02 CDT, the world broke into rejoicing as
>Steve Baker <sjbaker1 at airmail.net>  said:
>> S Jackson wrote:
>> > 
>> > Do any of ya'll know where I can get some more info about the 2GB file
>> > size limitation in Linux?  Is the VFS going to be updated in 2.4 to
>> > support large files?  Are there currently any patches I can apply to use
>> > big files?  I'm trying to integrate Linux into a production environment,
>> > and this is a big stumbling block (although our current OS, SCO
>> > Openserver, has the same problem).  Please, if you have any info let me
>> > know.  Thanx.
>> 
>> As another *wild* thought.  Can DOS file systems have >2Gb files?
>> If so, you could format your large partition as a DOS drive (yuk,
>> ack!) and mount it under Linux.  I have no idea if that would
>> work.
>
>I was at the talk last week in Atlanta at ALS by the guys at SGI that
>are working on the XFS project.  I put a direct question about the
>infamous "2GB limit" to Jim Mostek, asking if XFS did anything about
>the limitations of file size by VFS on 32 bit systems.
>
>As I expected, he indicated that XFS does not affect the 32 bit limit
>at the VFS level.  (The question was asked so that I could have a good
>quote from someone who writes filesystems for a living to address the
>fallacy.)
>
>The 32 bit limit on file size is no longer, even for EXT2, an issue
>that relates to the filesystem.  EXT2 can already support 2TB files on
>64 bit systems.  Any filesystem that uses the standard VFS interface is
>limited to 32 bit __offset values on IA-32 systems.