How many files can I have safely in a subdirectory?

Charles Riley criley at
Tue Sep 1 17:20:32 UTC 2009


I'm not sure if it's still the case, but there used to be a limit to how many subdirectories a directory can have.  32k, to be exact.  We ended up creating our own (application level) directory hashing algorithm to work around it several years ago.  This might only be a kernel 2.4 thing though.

I'm unaware of any limit to number of files.  However once the number of files in a directory gets above about 64k, filesystem performance will significantly decrease unless the filesystem has the dir_index option.  dir_index can be specified at filesystem creation or added later using tune2fs (an fsck is required).


Charles Riley
eRAD, Inc.

----- Original Message -----
From: "z0diac" <web2009 at>
To: ext3-users at
Sent: Sunday, August 30, 2009 12:00:12 PM GMT -05:00 US/Canada Eastern
Subject: How many files can I have safely in a subdirectory?

Ok, I'm running a vBulletin forum (3.8.4) and found that all user attachments
go into 1 single directory for each user. For each attached file in the
forum, there's 2 files on disk (*.attach and *.thumb), for pictures that is.

One user already has over 100,000 attachements, thus, over 200,000 files in
his attach directory.

Someone recently told me to 'keep an eye on it' because certain setups can't
hold more than X number of files in a single directory. Yet someone else
said I could have over 1 trillion files in a single directory if the HDD was
large enough...

Here's my setup:

linux version: 2.6.18-92.1.10.el5
php: 5.1.6
mySQL: 5.0.45
File system: ext3

vB support has told me any limitation there might be, will not be the result
of vB, so now I'm looking at either Linux and the way it handles files, or
the ext3 file system.

Does anyone know if I can just keep going with putting files into one
directory? (there will be over 1million probably by year's end. Hopefully
not more than 5 million ever).

And, will having so many files in a single directory cause any performance
problems? (ie: slowdowns)

My only option is to hire a coder to somehow have it split the 1M+ files
into several subdirs, say 50,000 per subdir. But even though it's messy, if
it really doesn't make a difference in the end whether they're in 50
subdirs, or just 1 dir, then I won't bother (and can sigh a breath of

Thanks in advance!!
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