[CentOS] Disk read io very high, but no process perform io read

Fri Mar 12 08:35:09 UTC 2021
Simon Matter <simon.matter at invoca.ch>

Hi,

You said that you have multiple systems running this same application.
But, do they work with the same data on disk or are there big differences?

>From how I understand the figures below, your buff/cache seems a bit low
if you read a lot of data from disk. If you read a lot of data and
filesystem caches are slow, it will result in heavy reading from disk
directly.

One more thing comes to mind: is your hardware behaving fine? I mean, if
your storag has difficulties to read data from disk due to hardware
issues, this could also lead to such problems you're facing.

Regards,
Simon

>
> yes. I suspect it has something to do with swapping. but swap is turned
> off on this server.
> here is the result of free -m.
>  total        used        free      shared  buff/cache   available
> Mem:         128174       97449       24400        4158        6325
> 25232
> Swap:             0           0           0
>
>
> We have other servers. The processes running on these servers are same.
> but on other servers, the size of buff/cache is larger than the size on
> the server which experienced the problem and the size of "free" is smaller
> than the size on the server which experienced the problem.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> �� 2021-03-10 14:30:00��"Thomas Stephen Lee" <lee.iitb at gmail.com> ���
>>On Sat, Mar 6, 2021 at 6:37 AM yf chu <cyflhn at 163.com> wrote:
>>>
>>> no, not vm
>>>
>>>
>>>
>>>
>>> | |
>>> yf chu
>>> |
>>> |
>>> ���䣺cyflhn at 163.com
>>> |
>>>
>>> ǩ���� ���������ʦ ����
>>>
>>> On 03/05/2021 23:37, Matthew Miller wrote:
>>> On Fri, Mar 05, 2021 at 03:54:14PM +0800, yf chu wrote:
>>> > We have experienced a very weird problem. The load of the server
>>> machine is very high. We use "pidstat" and find that the disk read io
>>> is very high.
>>>
>>> Is this system a VM?
>>>
>>> --
>>> Matthew Miller
>>> <mattdm at fedoraproject.org>
>>> Fedora Project Leader
>>
>>Hi,
>>
>>Is this due to swapping?
>>
>>what is the output of
>>
>>free -m
>>
>>---
>>Lee
>>_______________________________________________
>>CentOS mailing list
>>CentOS at centos.org
>>https://lists.centos.org/mailman/listinfo/centos
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
>