[CentOS] Slow performance

[John R Pierce]

> Try running "hdparm -Tt /dev/sda"  replace /dev/sda with the device name
> for your hard disks.  After running that post back here with the results.
>
> You can also install sysstat and use the sar command to see if your system
> is indeed spening a lot of time waiting on disk reads and writes.
>
>   


and for bonus points, from that same sysstat package...

    iostat -x 5

during a highly disk intensive session.  Ignore the first sample output, 
thats average since boot, the 3 means sample every 5 seconds.   this 
prints a wealth of useful information on the state of disk IO on a per 
drive basis.


btw, a rather useful performance tool for linux systems -> 
http://www-128.ibm.com/developerworks/aix/library/au-analyze_aix/index.html

(originally for AIX, its been ported to Linux... catch-22, its output is 
best processed by an Excel spreadsheet to product graphs... but you can 
use it on its own.)