ext3 fs directory limit

P1

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Oct 22, 2009, 4:34:24 PM10/22/09

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There is apparently a subdirectory limit of 32,000 on ext3 file systems.
How are people getting around this? I have a mail server that just
reached that number of users and I'm unable to create more.

Thanks,
Paul

Michael John Ruff

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Oct 22, 2009, 6:05:31 PM10/22/09

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Hello Paul

If you can create another directory called home1 and store the user
durectories in there.

Mike

P1

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Oct 22, 2009, 6:34:13 PM10/22/09

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Yeah, I thought about that, but then I'd have to figure out how to tell
Postfix and Dovecot where to look for those, not sure if that'd be possible.

David W. Hodgins

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Oct 22, 2009, 9:28:34 PM10/22/09

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On Thu, 22 Oct 2009 16:34:24 -0400, P1 <p...@fhri.org> wrote:

> There is apparently a subdirectory limit of 32,000 on ext3 file systems.

I wasn't aware of any such limit. Do you have the Dir Index option
turned on for that filesystem? On my system, where I do have it ...

$ fsstat /dev/sda8|grep Index
Compat Features: Journal, Ext Attributes, Resize Inode, Dir Index

If you don't have it, you can use "tune2fs -O dir_index /dev/????"
followed by "e2fsck -D /dev/????". This should be done on the
filesystem while it is not mounted, preferably, right after a full
backup. See "man tune2fs" for details.

Regards, Dave Hodgins

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J.O. Aho

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Oct 23, 2009, 1:00:05 AM10/23/09

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The subdirecotry limit is 31998, symlink limit is 32000 (per inode), and don't
forget that ext3 also has inode limitations, which will cause trouble in a
file system with a lot of files.

Don't use ext3, there are quite many other options like reiserfs, reiser4,
jfs, xfs. The two later are industry standard file systems and all of them
don't have the inode problem as ext3 has.

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//Aho

F. Michael Orr

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Oct 23, 2009, 11:08:39 AM10/23/09

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Actually, that's not entirely accurate. The actual limit is 32766
(32K-2). All filesystems have a limit, though they vary. That of reiser
is 64k, but it is a limit nonetheless. I don't know about xfs, but jfs
is 32k as well (at least the AIX flavor). UFS on Solaris is 32k as
well. The biggest I have found is WAFL on NetApp, which has a non-magic
number limit of 100,000.

The simplest (though kludgy) solution is to create another directory,
move many of your existing directories to the new directory, and replace
them with symlinks in the old directory. Symlinks aren't hard, and thus
aren't subject to the 32k limitation. This of course requires constant
babysitting, but it will get around much of the problem.

Davorin Vlahovic

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Oct 23, 2009, 12:14:29 PM10/23/09

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[Fri, 23 Oct 2009 10:08:39 -0500] F. Michael Orr je napisao/la:
> The simplest (though kludgy) solution is to create another directory,
> move many of your existing directories to the new directory, and replace
> them with symlinks in the old directory. Symlinks aren't hard, and thus
> aren't subject to the 32k limitation. This of course requires constant
> babysitting, but it will get around much of the problem.

create a directory for every beginning letter...

a/ -> aardvark, avokado...
b/ -> borg, babysitter....
c..
d..

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You, you, and you: Panic. The rest of you, come with me.

P1

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Oct 23, 2009, 12:26:29 PM10/23/09

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XFS does seem promising, thanks for that suggestion, I'll have to try it
out.

P1

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Oct 23, 2009, 12:28:22 PM10/23/09

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Thanks Mike, that is a good solution I think. At least in the interim,
it's quick and easy to implement. I'll still experiment with XFS as a
possible permanent solution, but this will get me back up and running
for a while.