Question about inodes

[Lars <sunberg@xxxxxxxxx>]

Hello!

I've always thought at indes as something uniq on every file on the
same file system. Today, I saw something weird that tickled my theory
about this. I found two folders, on the same filesystem that had the
same indoe. It is inode 1. Here is some info..


[root@test ~]# ls -lid /sys
	1 drwxr-xr-x 11 root root 0 Jul 25 13:06 /sys

[root@test ~]# ls -lid /dev/pts
	1 drwxr-xr-x 2 root root 0 Jul 25 13:06 /dev/pts

[root@test ~]# df
	Filesystem           1K-blocks      Used Available Use% Mounted on
	/dev/mapper/VolGroup00-LogVol00
	                      36756152   2138060  32720828   7% /
	/dev/hda1               101086     11818     84049  13% /boot
	tmpfs                   253652         0    253652   0% /dev/shm

[root@test ~]# ls /sys/
	block  bus  class  devices  firmware  fs  kernel  module  power

[root@test ~]# ls /dev/pts/
	0

[root@test ~]# stat /sys/ ; stat /dev/pts
	  File: `/sys/'
	  Size: 0               Blocks: 0          IO Block: 4096   directory
	Device: 0h/0d   Inode: 1           Links: 11
	Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
	Access: 2008-07-28 07:51:41.543581362 -0100
	Modify: 2008-07-25 13:06:46.705937679 -0100
	Change: 2008-07-25 13:06:46.705937679 -0100
	  File: `/dev/pts'
	  Size: 0               Blocks: 0          IO Block: 4096   directory
	Device: bh/11d  Inode: 1           Links: 2
	Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
	Access: 2008-07-28 07:51:53.067829410 -0100
	Modify: 2008-07-25 13:06:46.707937375 -0100
	Change: 2008-07-25 13:06:46.707937375 -0100

[root@larscen ~]# fdisk -l
	Disk /dev/hda: 40.0 GB, 40020664320 bytes
	255 heads, 63 sectors/track, 4865 cylinders
	Units = cylinders of 16065 * 512 = 8225280 bytes

	   Device Boot      Start         End      Blocks   Id  System
	/dev/hda1   *           1          13      104391   83  Linux
	/dev/hda2              14        4865    38973690   8e  Linux LVM

[root@test ~]# uname -a
Linux test 2.6.18-92.el5 #1 SMP Tue Jun 10 18:49:47 EDT 2008 i686 i686
i386 GNU/Linux


As you see, both /sys and /dev/pts have the same inode. This is not an
issue, but a question.
I can see that the device is not the same on these two files/folders,
but they are on the same fs..

I searched for a couple of more inodes (find / -inum NUMBER) to find
out that this is very common..

The OS is centos5, but the same seems to be the case on debian.


Side question: How many % used inodes critical to much? I have a
server that have around 66% used inodes,
and wonder if I should do something or if I should let the problem fix itself.

Thanks
  Lars
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