Date: Sun, 09 Nov 2008 12:16:18 +0000 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Jeremy Chadwick <koitsu@freebsd.org> Cc: freebsd-questions@freebsd.org, no-spam@people.net.au Subject: Re: UFS2 limits Message-ID: <4916D492.5040406@infracaninophile.co.uk> In-Reply-To: <20081109024046.GB27423@icarus.home.lan> References: <50261.1226194851@people.net.au> <20081109024046.GB27423@icarus.home.lan>
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Jeremy Chadwick wrote:
> I don't want to change the topic of discussion, but I *highly* recommen=
d
> you ***stop*** whatever it is you're doing that is creating such a
> directory structure. Software which has to iterate through that
> directory using opendir() and readdir() will get slower and slower as
> time goes on.
With the implementation of UFS_DIRHASH the practical limit on the
size of directories is now a great deal larger. In particular
the slow down caused by linear search through the contents has been=20
eliminated. See ffs(7). 10,000 files or sub-directories, whist
not a particularly elegant setup, is actually not unworkable
nowadays.
As for the maximum number of subdirectories it is possible to create
on UFS2 -- it is limited by the inode structure to a 16 bit quantity.
% jot 100000 1 | xargs mkdir -v
[...]
32725
32726
32727
32728
32729
32730
3273mkdir: 32766: Too many links
mkdir: 32767: Too many links
mkdir: 32768: Too many links
mkdir: 32769: Too many links
mkdir: 32770: Too many links
mkdir: 32771: Too many links
[...]
Which is 32768 - 2 for the '.' and '..' links. Trying to create too
many subdirectories just results in mkdir failing: the filesystem
itself is not damaged.
Cheers,
Matthew
--=20
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
Kent, CT11 9PW
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