Sync Errors Corrected after unclean shutdown during file transfer

[ElJimador]

Hello. Thanks to a faulty UPS I had an unclean shutdown on my HOME server in the middle of a big file transfer directly to a disk share and running the parity check required after I unchecked the box to write corrections to parity. Despite this I wake up this morning to 735 sync errors corrected. (The check was barely halfway through since with my massively underpowered CPU and now dual 12TB parity, checks take around 6 days now.) Anyway I've paused the check and am attaching diagnostics here if needed but what I really need to know is, do sync errors corrected only overwrite parity, or are corrections also (or only?) being written to data drives from parity? If it's only parity being re-written should I resume the check and let it complete no matter how many more errors may register (assuming the result would be the same as doing a new config with all drives in their current assignments and letting parity be completely re-written)? Or if data drives are being overwritten (with possibly corrupted data given the circumstances) is there any way to pinpoint where those errors might be before I stop the check, and then what would next steps be from there? Thanks.

home-diagnostics-20240327-0441.zip

[JorgeB]

A few sync errors are normal, even expected, after an unclean shutdown, just run a correcting parity check.

[ElJimador]

1 hour ago, JorgeB said:

A few sync errors are normal, even expected, after an unclean shutdown, just run a correcting parity check.

Thanks Jorge. So just to be sure on this, corrections are only written from data drives to parity and never the other way around? And since the current parity check I have paused is a correcting check (showing 735 corrections already, whatever I intended), I should just go ahead and resume it? And final question, if I do that and the error count continues to rise, at what point would you be concerned and pause it again? I've had data loss in the past from drives dropping off during a parity check so that's my biggest concern here. And though it'd be slower to do a new config and let parity be completely rewritten again, if it's in any way safer I wouldn't mind. Appreciate your help as always.

[itimpi]

7 minutes ago, ElJimador said:

Thanks Jorge. So just to be sure on this, corrections are only written from data drives to parity and never the other way around? And since the current parity check I have paused is a correcting check (showing 735 corrections already, whatever I intended), I should just go ahead and resume it? And final question, if I do that and the error count continues to rise, at what point would you be concerned and pause it again? I've had data loss in the past from drives dropping off during a parity check so that's my biggest concern here. And though it'd be slower to do a new config and let parity be completely rewritten again, if it's in any way safer I wouldn't mind. Appreciate your help as always.

Might as well let the check continue.  It will only be updating parity to make it conform to the current data disks.

[ElJimador]

9 hours ago, itimpi said:

Might as well let the check continue.  It will only be updating parity to make it conform to the current data disks.

Okay, thanks for confirming. The parity check is resumed and I'll keep this open until it completes just in case any other issues arise but I'll be sure to remember to come back and mark it solved then. Thank you!