CentOS 5.9: unusual HDD activity when idle

When I boot up my CentOS 5.9 box and leave it unused for a while, it
begins thrashing the hard drive as if it's doing a hard disk scan. Do
fedora based distros like CentOS have some sort of automated hard disk scan
that starts up when the system is idle?

iotop should tell you what's making the HDD busy, debian and suse has it so I assume cent does too.

CentOS has iotop in the base repository.

magellan said:

When I boot up my CentOS 5.9 box and leave it unused for a while, it
begins thrashing the hard drive as if it's doing a hard disk scan. Do
fedora based distros like CentOS have some sort of automated hard disk scan
that starts up when the system is idle?

Click to expand...

To answer your question, yes it does. It has a tool called mlocate which populates the locate.db file. That way when you type


It can return instantly. To kick this off manually run


However, unless your file system is changing constantly, there is usually only one large hit initially, then after that the locate database stays mostly static (relative to the large number of files on your system that don't change often)

There was no iotop or topio binary in my installation of CentOS 5.2 (upgraded to 5.9).

Just out of curiosity, does CentOS somehow schedule long or short SMART disk diagnostic
scans to occur?

If you used a base installation, you have to install iotop.

OK, I've got iotop installed. Now I just have to wait for the next disk thrashing incident to occur.

We have a winner, result of disk thrashing and iotop:

find /usr/share/man/man3 -name * -xtype f -size +0 -ctime 0

What exactly is this find command trying to find?