I am currently running 6.7.2 and ran it to a problem, I will use scenarios to try to be succinct:

 

Scenario 1:  was pre-clearing a 8TB and 4TB via UD in a usb 3.1 dual slot external dock.  Preclear failed on Post-Read on the 4TB.  Researching lead me to shutdown server and run memtest for 48hrs.  No issues.  Then did digging and found that the Preclear plugin has failed on Post-Read when running concurrent disks in a few scenarios.  Ran Preclear on each disk indivdually, 2 cycles and passed.

 

Scenario 2:  I need to preclear 4 10TB to swap data disks to increase array capacity.  Based on Scenario 1 results, I opted to use patched (Bin-Hex) fast_preclear.sh script.  Running 2 drives concurrently in same dock, one drive became unresponsive during zeroing 30hrs in.  The other drive continued to move along until I accidentally terminated the screen session (not detached, killed).  Which has led to...

 

Scenario 3: I am currently running preclear concurrently on the 2 10TBs except one is via plugin and gfjardin script, and the other a screen session and fast_preclear.sh. Both are progressing... but the plugin is Pre-Reading at 186mb/s while the scripts is moving at 68mb/s. In both prior scenarios the speed of concurrent drives was identical... at around 180 mb/s

 

 

Questions:

 

1.  Why would one drive drop off in scenario 2 (flaky dock?).  The server has 64gb ram so I don't think Ram availability is issue.  (I don't have slots available internally otherwise I would run off of native sata bus instead of dock)

 

2.  MORE IMPORTANTLY: should the speed discrepancies between plugin and script be cause for concern.

 

Thanks for any help!

 

 

This isn’t really an answer to your questions, but I wanted to point out that preclear is no longer required for adding a drive to your array (some people do use it for stress testing drives though). UnRAID will now clear the drives in the background. The plugin hasn’t been updated in a while and quite a few people have reported issues. The scripts you mention may also be outdated.

Thank you @wgstarks

 

I am using the script / plugin to stress-test the drives prior to adding them to array.  While it may not guarantee drive robustness... it does give added piece of mind.

 

Cheers.