FreeBSD 11.2 - all processes hang in D state

[Anton Yuzhaninov]

On 10/5/18 4:51 AM, Christos Chatzaras wrote:
> The problem is that all processes that are related somehow to /home stuck in D state.
> 
> I was able to shutdown mysql which has the data in /var partition.
> 
> The servers use UFS SU+J but I don't think it's related as they run stable for a long time.

There are many reasons why process cat stuck in D state. Most common:
- bad HDD. Be sure to run SMART long self-test and examine 'smartctl -a'
output. Even better is to run smartd configured to do periodic tests and sned
mail in case of failure
- some bug in UFS code
- some bug in disk controlled driver

Suggestions to get more info:

1. top -SH output will be more useful than ps - it will show wait channel for
blocked processes.
2. run gstat and check what it will show when problem will happen
3. Configure syslog to forward kernel messages to other host to get full logs.
In case of problems with disk/FS not all messages will be written to local
/var/log/messages