Re: BIG files & file systems

From: Hans Reiser (
Date: Mon Aug 05 2002 - 08:42:18 EST

Stephen Lord wrote:

>>For a LinuxWorld presentation in August, I have asked each of the
>>4 journaling filesystems (ext3, reiserfs, JFS, and XFS) what their
>>filesystem/filesize limits are. Here's what they have told me.
>> ext3fs reiserfs JFS XFS
>>max filesize: 16 TB# 1 EB 4 PB$ 8 TB%
>>max filesystem size: 2 TB 17.6 TB* 4 PB$ 2 TB!
>>#: think sparse files
>>*: 4 KB blocks
>>$: 16 TB on 32-bit architectures
>>%: 4 KB pages
>>!: block device limit
>If those are the numbers you are presenting then make it clear that
>for XFS those are the limits imposed by the the Linux kernel. The
>core of XFS itself can support files and filesystems of 9 Exabytes.
>I do not think all the filesystems are reporting their numbers in
>the same way.
You might also mention that I think the limits imposed by Linux are the
only meaningful ones, as we would change our limits as soon as Linux
did, and it was Linux that selected our limits for us. We would have
changed already if Linux didn't make it pointless to change it on Intel.
 Reiser4 will have 64 bit blocknumbers that will be semi-pointless until
64 bit CPUs are widely deployed, and I am simply guessing this will be
not very far into reiser4's lifecycle. Really, the couple of #defines
that constitute these size limits, plus some surrounding code, are not
such a big thing to change (except that it constitutes a disk format


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