The maximum number of files under a folder

[Andreas Dilger]

On Mar 17, 2008  09:32 -0400, Theodore Ts'o wrote:
> On Mon, Mar 17, 2008 at 03:40:36PM +0800, liuyue wrote:
> > Theodore Tso,
> > 
> > 	In 64bit system, directory size can not be bigger than 2GB?
> 
> No, because the high 32-bits for i_size are overloaded to store the
> directory creation acl.

I think we should change the code (kernel and e2fsprogs) to allow
i_size_high for directories also.

> In practice, you really don't want to have a directory that huge
> anyway.  Iterating through it all with readdir() gets horribly slow,
> and applications that try do anything with really huge directories
> would be well advised to use a database, because they will get *much*
> better performance that way....

Actually, for many HPC applications they never do readdir at all.
The job creates 1 file/process and always uses a predefined filename
like {job}-{timestamp}-{process} that it will directly look up.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.