Monthly non-correcting Parity check showed 1 error, but subsequent correcting check found no errors

[Rusty6285]

Howdy,

 

A little confused by the behaviour from my server this month. As per title, I have a monthly non-correcting parity check that found 1 error. However, assuming this to be a bit flip or similar, I ran a correcting check the next day and it found no errors.

 

When I look in my syslog, I see these entries from the first run:

 

 

Quote

Mar  1 00:00:02 Nostromo kernel: mdcmd (42): check 
Mar  1 00:00:02 Nostromo kernel: md: recovery thread: check P ...

 

 

Quote

Mar  2 03:29:09 Nostromo kernel: md: recovery thread: P corrected, sector=27343716288
Mar  2 03:29:15 Nostromo kernel: md: sync done. time=98953sec
Mar  2 03:29:15 Nostromo kernel: md: recovery thread: exit status: 0

 

Does this suggest that the first run was actually a correcting parity check? my schedule has 'Write corrections to parity disk:' set to 'NO'. Any reason Unraid would decide itself to make a scheduled check be a correcting check, despite this setting?

 

Edit: In the image below, the 2nd correcting parity operation I ran dated 2023-03-03.... shouldn't that say Parity-Sync if it was correcting?

 

Thanks!

 

 

Edited March 3, 2023 by Rusty6285

[itimpi]

20 minutes ago, Rusty6285 said:

Edit: In the image below, the 2nd correcting parity operation I ran dated 2023-03-03.... shouldn't that say Parity-Sync if it was correcting?

No - it would say it was a parity-sync if it was building parity rather than checking it.

 

if you install the Parity Check Tuning plugin then for new checks the history entries will tell you if the checks are correcting or non-correcting.   This will happen even if you do not use the plugin’s facilities to run checks in increments.

[Rusty6285]

Thanks @itimpi, I've installed the plugin to hopefully capture that info on future runs (the updated 'history' tab does show some extra cols after install, but does not suggest if it was correcting that I can see, at least for runs prior to install).

 

Working with the information I do have though, does it suggest that the scheduled monthly run was correcting? and if so, it shouldnt have been according to the out the box setting...

[itimpi]

9 hours ago, Rusty6285 said:

Thanks @itimpi, I've installed the plugin to hopefully capture that info on future runs (the updated 'history' tab does show some extra cols after install, but does not suggest if it was correcting that I can see, at least for runs prior to install).

 

Working with the information I do have though, does it suggest that the scheduled monthly run was correcting? and if so, it shouldnt have been according to the out the box setting...

The extra columns only get populated for checks that are run after the plugin is installed.

 

If nothing else this will allow you to get confirmation of whether Unraid started a correcting or non-correcting check as the plugin looks at the characteristics of a running check (i.e. AFTER it has been started) and not what it was set to be at the time it was initiated.

 

Just a thought though, you might want to make a small change to the settings page for the scheduled check and hit apply just in case the displayed fields are not matching the stored ones on the flash drive as doing that should cause them to be rewritten.