Can someone tell me, why is this 100% used on the /?

How can I fix this problem? I'm not a unix admin, I'm a programmer but can read the books.

[root@datasrv /]# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda2              7757352   7757248         0 100% /
/dev/sda1               248895     15027    221018   7% /boot
/dev/sda9            120098680   3173944 110725656   3% /data
tmpfs                   777052         0    777052   0% /dev/shm
/dev/sda5              3882508    128136   3553964   4% /home
/dev/sda7              1945132     35888   1808840   2% /tmp
/dev/sda6              7757320   4728956   2627948  65% /usr
/dev/sda3              7757352    571420   6785512   8% /var

Follow up:

I deleted some files then ran my rsync program which syncs from a windows mount share drive to a USB drive. It doesn't write to the local Centos disk as far as I know. Then suddenly the disk drive is full again, why? Does rsync do something that creates lots of files somewhere?

  • 3
    as root, run du -sh * in / and see where all the space has gone. – Tom O'Connor Jul 27 '10 at 11:28
  • 1
    My bet would be on /opt or /root or both ... – Sven Jul 27 '10 at 11:32
  • 1
    Heh. We've got a FreeBSD box here that claims that / is 108% full and it still runs fine, maybe it's time to go to BSD. ;-) ;-) – Brian Knoblauch Jul 27 '10 at 12:44
  • What is the full rsync command you're running? – Matt Jul 27 '10 at 14:56
  • Is this a virtual machine or physical? – JMeterX Jul 19 '13 at 19:57

Find big files and remove them if possible:

find / -mount -size +8096 -ls
find / -mount -name core -ls
du -sh /* (and repeat for subsequent dirs on /)

Probably something is flooding your / or you have to many old kernels. Cleaning up will help, your / should be big enough because you've a seperated /var and /usr (and /data ...).


Use ncdu.


If you want to check filesize of every directory right in the root, you can use du -h --max-depth=1 /. It'll take quite a while.


Check your .xsession-error file. You might refer to this post and see if it helps.

However, since you are running CentOS, I would look in /etc/x11/xinit for the xsession file. Also, remove the "quotation marks" around the file and get rid of $HOME.


One thing I see that causes the drive to fill up is the root mail. You might need to empty out your mail for root or whatever other user you need.


du -sh /var/mail/*

That should list your mailbox size. If one of them is huge like root just run this command to empty it


> /var/mail/root

Make sure you add the greater sign

Your done!

  • /var is on a separate volume. Truncating root's email will not make any free space on / – Mircea Vutcovici Jun 6 '17 at 2:40
  • It worked for me today – Cesar Bielich Jun 6 '17 at 2:41

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