Re: 2.1.108: file sizes > 2GB with ext2?
Thu, 30 Jul 1998 22:24:43 -0400

Date: Wed, 29 Jul 1998 14:09:37 -0800
From: Steven Roberts <>

Seomthing just hit me on this, does this mean ext2 partitions made on a
64-bit arch aren't compatible with those made on a 32-bit arch (or is it
just a in running kernel sizeof(long) limitation)?

Am shuffling some servers around and was about to move a drive from an
intel box to an alpha...

When you create a file greater than 2GB on a 64-bit platform, it sets a
read-only compatibility flag. This prevents you from mounting the file
read/write on a 32-bit platform, but you can still mount the ext2
partition read-only.

If you delete the >2GB file, and then run e2fsck, e2fsck will notice
that there are no longer large file files on the machine, and remove
that compatibility flag, thus allowing you to mount the filesystem
read/write on 32-bit platforms again.

If and when someone does the work to support full 64-bit files on 32-bit
platforms, it would be possible for a 32-bit Linux system to be able to
deal with large files; at the moment, though, 32-bit ext2
implementations know just enough about large file support to not be
confused when they see a >2GB file for reading --- although they will
only let you look at the first 2GB of that large file.

- Ted

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