Question about inodes

Question about inodes

[Lars]

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

Re: Question about inodes

[Adam T. Bowen]

[-- Attachment #1: Type: text/plain, Size: 3532 bytes --]

Hi Lars,

       If you are using devfs then /dev is a different file system (as 
is /dev/pts if you are using devpts).  Doing:

       df / /dev /dev/pts

should show something like:

Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda3            234361956  10748068 211516944   5% /
-                       996564       128    996436   1% /dev
devpts                       0         0         0   -  /dev/pts

Cheers

Adam

Lars wrote:
> 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
> --
> To unsubscribe from this list: send the line "unsubscribe linux-admin" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 252 bytes --]

Re: Question about inodes

[Glynn Clements]

Lars wrote:

> 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

Inode numbers are only unique within a filesystem. /sys and /dev/pts
are separate filesystems.

> [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

"df" only lists filesystems which correspond to block devices. Use
"mount" or "cat /proc/mounts" for a complete list.

> 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..

No they aren't.

/proc, /proc/bus/usb, /sys, /dev, /dev/pts, and /dev/shm are usually
separate filesystems (/dev might not be if you're using static device
files rather than devfs).

-- 
Glynn Clements <glynn@gclements.plus.com>