Re: 2.1.108: file sizes > 2GB with ext2?

Stephen C. Tweedie (sct@redhat.com)
Fri, 31 Jul 1998 10:49:13 +0100


Hi,

On Thu, 30 Jul 1998 11:09:27 +1200, Chris Wedgwood
<chris@cybernet.co.nz> said:

> On Wed, Jul 29, 1998 at 11:19:53PM +0200, Andi Kleen wrote:
>> They are compatible, because ext2 internally uses 32bit block
>> numbers (and a block on a normal HD is 512bytes). It is purely a VM
>> limitation.

> So - what does a (say) 5GB file look like when a disk is moved from
> an Alpha to an Intel box - and what happens you you open/seek/mmap
> it?

You cannot mount a filesystem containing >2GB files on a 32bit
machine. What happens is that any attempt to create such a file on a
64bit machine sets one of the ext2 superblock compatibility flags, and
32bit machines detect and reject the flag. e2fsck will clear the
compatibility flag if it finds no >2GB files left on the filesystem.

--Stephen

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