NAS-140206 / 27.0 / Clarify code comments and logging messages related to disk retaste

[themylogin]

The root cause of the hanging job issue was removing multiprocessing.set_start_method('spawn') when process pool was removed. This is confirmed by the absence of the bug in 26.0.0-BETA.1 where process pool is still present.

[themylogin]

http://jenkins.eng.ixsystems.net:8080/job/master/job/custom/2130/

[themylogin]

https://ixsystems.atlassian.net/browse/NAS-140206

[themylogin]

time 2:00

[yocalebo]

The behavioral change of making the caller wait on retaste is profound and extremely intrusive. Why was that logic changed?

[themylogin]

@yocalebo I thought that's what was expected. The logging message says Done retasting disks on standby node. It should say Done scheduling retasting disks on standby node then? I can roll this back.

[yocalebo]

@yocalebo I thought that's what was expected. The logging message says Done retasting disks on standby node. It should say Done scheduling retasting disks on standby node then? I can roll this back.

Definitely not what is expected, let's just change the logging message.

[themylogin]

@yocalebo what about other retaste callers, should they wait or should they just schedule the retaste?

[yocalebo]

@yocalebo what about other retaste callers, should they wait or should they just schedule the retaste?

Just schedule it, they don't need to wait.