[CentOS] Re: Native Command Queueing

[John R Pierce]

Matt wrote:
>>> I was monitoring it with SAR and there was very high level of IOWait, meaning the drive was having a hard time.
>>>       
>
> How bad does the below look?  Dual core AM2 5600+ with 4G DDR2 and
> single SATA2 drive.
>
> Matt
>
> 10:10:01 AM       all     20.54      0.00      4.09     15.85     59.52
> 05:40:01 PM       CPU     %user     %nice   %system   %iowait     %idle
> 05:50:01 PM       all      7.20      0.00      2.49      5.08     85.23
>   
...


use `iostat -x 5` for 5 second intervals with a lot more detail on disk 
IO operations.  ignore the first output sample, thats the average since 
last boot..    iostat is part of the sysstat package, yum install 
sysstat, if you don't already have it.