[6.9.2] High CPU usage + difference between dashbord and top command values

[xiab]

Hi,

 

I noticed a high CPU usage on my unraid machine. I'm trying to find out why.

 

 

First of all, is it normal to have two different values between the unraid dashboard and the "top" command?

Indeed, on the dashboard, I see the CPU is used at 100% as shown in the first screenshot. But, when I run the "top" command in the console, I see that the CPU is used less than 25% (sum of the first lines), see the second screenshot.

 

 

 

Why the difference between the two?


Next, according to you, why I have such a high CPU consumption? I feel that the NAS is very slow.

Let me know if you need more information.

Thx for your help


More details:
UNRAID v6.9.2
CPU : AMD Athlon™ II X2 250 @ 3000 MHz (2 cores)
RAM : 4Go DDR3
Disk (filled at 80%) : HDD 1 To + HDD 2To + HDD 2To (parity)

[JorgeB]

On 9/4/2021 at 4:44 PM, xiab said:

First of all, is it normal to have two different values between the unraid dashboard and the "top" command?

Yes, dashboard includes iowait.

[xiab]

Thanks for your answer.

So the difference is explained by an important iowait if I understand correctly. Is it possible to integrate the iowait in the result of the top command or in another equivalent command? The objective is to find out which process generates this high iowait.

In parallel, how can I reduce iowait?  Would a cache disk be enough? If not, what are the other possible solutions?