[CentOS] Strange performance issue on CentOS 6.7 server

[Warren Young]

On Feb 3, 2016, at 2:26 PM, Alfred von Campe <alfred at von-campe.com> wrote:
> 
> On Feb 3, 2016, at 16:13, Warren Young wrote:
> 
>> A dying hard disk can do it.  HDDs try to silently paper over I/O errors, but what they can’t hide is the time it takes to do this.  If your HDD is constantly correcting errors at the oxide layer, it will be reeeeeallly sllllow.
>> 
>> You can try running SMART tests on it, though that’s not guaranteed to show the problem.
> 
> Well, it’s not “a” disk: it’s a HW RAID of about dozen (server grade) drives

smartctl can see through several different types of RAID controller to the underlying physical disks via its -d option.