How to find out which process is causing Disk I/O?

[buedi]

Hi everyone,

I am still at 25.7 and since a few weeks I encounter system instabilities and increased Disk I/O. Both might not be related, but Disk I/O is something I want to look into first, because it is also visible from the outside.

My OPNsense box has a Disk activity LED. Usually this one flashes up once every 5-10 seconds I would say. Recently it is more like every 0,5 seconds, sometimes even constantly on for a few seconds. When I set up my OPNsense around a year ago, I paid attention to minimize logging as much as possible, but either things might have changed due to new functionality / updates, or my system is having issues which is causing more logging.

I lack the knowledge in BSD how to find out which processes or parts of OPNsense are causing the Disk I/O and I would appreciate if someone could point me in the right direction.

I am not saying that OPNsense is causing the crashes I encounter, but maybe it is logging some faults that lead to the crash after a while. Also, if possible, I want to find the root cause of the Disk I/O to bring it down again for less heat and wear of the SSD.

Any help is appreciated very much.

Thank you very much in advance :-)

[pfry]

Have a look at Hostwatch - high disk writes.

[buedi]

Thank you very much. I figured before I track this down, I upgrade to 26.1 instead... and now it got worse. Since this is another version, I will open another thread in the 26.1 section.

To have the answer to my question here, just in case someone else stumbles upon it:

```
top -S -m io -o total
```

Shows the processes causing I/O.

[Patrick M. Hausen]

See other thread. Disable hostwatch. It's a new non-essential feature. It's going to mature but if it gives you trouble now, your firewall will work just as well with it disabled.