Is there  way to turn the parity check priority way down? On my system for some reason it slows everything to a crawl. 

There was a file transfer from a unassigned SSD at 17:10 that should have been about 150MB/s and taken less than a minute that took about an hour.

And at 05:00 Plex was doing a scan that usually only takes a few minutes that took aver 3 hours. I would much rather the parity check be slow.

As a note, I do have reconstruct write selected and I am running 6.8.0. I have not done any tests to see how other concurrent disk operation behave.

 

 

No - the parity check either runs full speed of not at all.   The nature of what a parity check is doing probably means that reducing its priority would have little effect anyway   There is an option to Pause and then Resume a parity check but this is a manual process,

 

if you only want the Parity Check to run In increments outside prime time you could install the Parity Check Tuning plugin to automate that process.

I thought that on 6.8 it more or less tries to tune itself to always leave reasonable bandwidth available for other operations.

3 minutes ago, Squid said:

I thought that on 6.8 it more or less tries to tune itself to always leave reasonable bandwidth available for other operations.

I thought that also...

5 hours ago, Squid said:

I thought that on 6.8 it more or less tries to tune itself to always leave reasonable bandwidth available for other operations.

I can tell you from my experience this morning, this is not true.  Transfers from the array were in the Kilobyte/s range while the parity check was finishing up. (Win10 telling me, it would be a more than a day until it completed.  Cancelled transfer...)   After parity check completed, it was 35 MB/s and higher depending on file size. (I was transferring files to a USB3 2.5" HD attached a WIn10 computer.)