Ufs

Количество директорий
There is a limit to how many subdirectories you can have in a single directory - that limit is 32765. This is tied to the how many hardlinks you can have to a single directory entry (32767: the value is stored in the inode as a signed 16-bit value) and every subdirectory contains a hardlink to its parent (the ".." entry.)

Количество файлов в директории
Неизвестно. Во всей системе - ограничение по количеству inode

FS с большим количеством inode, если они закончатся

Свободные inode
df -i -h Filesystem    Size    Used   Avail Capacity iused   ifree %iused  Mounted on /dev/ad8s1a     67G     60G    2.4G    96%  301087 8837087    3%   / devfs         1.0K    1.0K      0B   100%       0       0  100%   /dev

stat -x /bin/sh File: "/bin/sh" Size: 113180      FileType: Regular File Mode: (0555/-r-xr-xr-x)        Uid: (    0/    root)  Gid: (    0/   wheel) Device: 0,95  Inode: 2496543    Links: 1 Access: Tue Apr 13 18:35:25 2010 Modify: Sun Feb 24 20:50:53 2008 Change: Mon Sep 8 04:58:00 2008

fsdb -r /dev/ad8s1a Интерактивный режим команды inode 2496543 blocks

find -x / -inum 2496543 -exec stat -x {} \; File: "/bin/sh" Size: 113180      FileType: Regular File Mode: (0555/-r-xr-xr-x)        Uid: (    0/    root)  Gid: (    0/   wheel) Device: 0,95  Inode: 2496543    Links: 1 Access: Tue Apr 13 18:44:13 2010 Modify: Sun Feb 24 20:50:53 2008 Change: Mon Sep 8 04:58:00 2008