Use the following command:
hdparm -tT /dev/sda1
A good test result is this one:
# hdparm -tT /dev/sda1
/dev/sda1:
Timing cached reads: 21416 MB in 1.99 seconds = 10785.03 MB/sec
Timing buffered disk reads: 106 MB in 3.01 seconds = 35.16 MB/sec
If you try to install APC via WHM in cpanel and you get:
cpanel /usr/include/php/ext/pcre/php_pcre.h:29:18: error: pcre.h: No such file or directory
then you need to install PCRE-devel.
Follow the next step
Go to / and type
yum install pcre-devel
Now, go back to WHM and try to install again PCRE.