= Running fsck in CentOS 5=

It is apparently a very bad idea to run fsck on a mounted filesystem, even via single user mode. There are two good options for running it:
=== Boot from a CD ===
Boot from a CD with CentOS on it, and run it from the CD. Then none of your filesystems are mounted.

To do this, boot into Linux Rescue Mode:
<code>
boot: linux rescue
</code>

**DO NOT mount your filesystems when it asks you if you want to.** As noted above, you can't run ''fsck'' on a mounted filesystem.

Once you're in rescue mode, run ''fsck'' on the correct partition:
<code>
fsck -f /dev/sda1
</code>

If you've used the Linux LVM to create your partitions, you'll need to make those accessible before you run ''fsck'':
<code>
lvm pvscan
lvm vgscan
lvm lvchange -ay VolGroup00
lvm lvscan
</code>

Then you can run ''fsck'':
<code>
fsck -f /dev/VolGroup00/LogVol00 
</code>

=== Run on restart ===
If you type<code bash>bash# shutdown -Fr now</code>then CentOS will reboot and do a forced fsck, which will be done before the filesystems are mounted.