linux disk usage report inconsistancy after removing file. cpanel inaccurate disk usage report
- by brando
relevant software:
Red Hat Enterprise Linux Server release 6.3 (Santiago)
cpanel installed 11.34.0 (build 7)
background and problem:
I was getting a disk usage warning (via cpanel) because /var seemed to be filling up on my server. The assumption would be that there was a log file growing too large and filling up the partition. I recently removed a large log file and changed my syslog config to rotate the log files more regularly. I removed something like /var/log/somefile and edited /etc/rsyslog.conf. This is the reason I was suspicious of the disk usage report warning issued by cpanel that I was getting because it didn't seem right.
This is what df was reporting for the partitions:
$ [/var]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 9.9G 511M 8.9G 6% /
tmpfs 5.9G 0 5.9G 0% /dev/shm
/dev/sda1 99M 53M 42M 56% /boot
/dev/sda8 883G 384G 455G 46% /home
/dev/sdb1 9.9G 151M 9.3G 2% /tmp
/dev/sda3 9.9G 7.8G 1.6G 84% /usr
/dev/sda5 9.9G 9.3G 108M 99% /var
This is what du was reporting for /var mount point:
$ [/var]# du -sh
528M .
clearly something funky was going on. I had a similar kind of reporting inconsistency in the past and I restarted the server and df reporting seemed to be correct after that. I decided to reboot the server to see if the same thing would happpen.
This is what df reports now:
$ [~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 9.9G 511M 8.9G 6% /
tmpfs 5.9G 0 5.9G 0% /dev/shm
/dev/sda1 99M 53M 42M 56% /boot
/dev/sda8 883G 384G 455G 46% /home
/dev/sdb1 9.9G 151M 9.3G 2% /tmp
/dev/sda3 9.9G 7.8G 1.6G 84% /usr
/dev/sda5 9.9G 697M 8.7G 8% /var
This looks more like what I'd expect to get.
For consistency this is what du reports for /var:
$ [/var]# du -sh
638M .
question:
This is a nuisance. I'm not sure where the disk usage reports issued by cpanel get their info but it clearly isn't correct. How can I avoid this inaccurate reporting in the future? It seems like df reporting wrong disk usage is a strong indicator of the source problem but I'm not sure. Is there a way to 'refresh' the filesystem somehow so that the df report is accurate without restarting the server? Any other ideas for resolving this issue?
