Please forgive me if this post is in the wrong area or if this has been definitively answered somewhere else.  I did search for answers, but maybe not as thoroughly as I could have.  I had an issue with my primary UnRaid server a few days ago after it ran it's monthly integrity check.  My parity drive, a Seagate EXOS X16 16TB drive, showed a fault and Unraid wouldn't bring it online.  It reported a UDMA CRC error count of 1126, which may be a symptom of the actual problem, and not the root cause.  I'm guessing cable.  I didn't get any emails about the issue, but did get a bunch of notifications in the web interface.  It's my own fault for not paying as close attention as I should have.  I received two new 16TB drives two days later, as I planned to add a second parity drive and to use the second drive to replace a 4TB drive in the array.

 

Things I've done since then:

1. I removed the problematic drive from the server, connected it to an external drive enclosure and ran a number of checks against it using Seagate SeaTools, all of which passed, including the fix all long task.
2. Ordered a replacement mini SAS cable, which will arrive today.
3. Installed one of the new 16TB drives into my primary UnRaid server, in the bay I had designated for the second parity drive, so the cable or port that is likely the cause of the issue is currently vacant, rebuilding parity for the array.  In addition to the single parity drive, I have three 16TB and four 4TB drives, all connected to the same ASR-72405 controller and none of those drives have reported any CRC errors.
4. I added the suspect drive to my backup UnRaid server and am currently running it through a preclear process.

 

When the preclear process is complete, so long as I don't see further CRC errors, I want to add the drive as a second parity drive on my backup server.  I've read that CRC errors shouldn't result in data loss because the server will resend data again until it completes successfully, and that the CRC errors are written to the drive itself, can't be reset.

 

So here are my questions:

1. Will the UDMA CRC errors themselves prompt UnRaid to disable the drive?
2. How do I get UnRaid to bring the drive back online?  Prior to taking it out of my primary server, I tried to just uncheck the box for attribute 199 to get it to not report on the error count, but it didn't seem to help, but the server has also been restarted a few times since then.

 

Here are some of the SMART attributes of the drive:

Raw read error rate:               206276673

Seek error rate:                      360254261

Power on hours:                     11087 (1y, 3m, 7d, 23h)

Command timeout:                 4295032833

UDMA CRC error count:          1126

31 minutes ago, charlesshoults said:

didn't get any emails

Setup Notifications to alert you immediately by email or other agent as soon as a problem is detected. 

 

Thank you for that part.  I apparently had notifications set up on both servers, but was using an expired password.

14 hours ago, charlesshoults said:

Will the UDMA CRC errors themselves prompt UnRaid to disable the drive?

UDMA_CRC errors are a connection problem, and if the problem is bad enough it can disable a disk.

 

14 hours ago, charlesshoults said:

How do I get UnRaid to bring the drive back online? 

https://wiki.unraid.net/Manual/Storage_Management#Rebuilding_a_drive_onto_itself but only do this after checking that the emulated disk is mounting and contents look correct.

 

14 hours ago, charlesshoults said:

I tried to just uncheck the box for attribute 199 to get it to not report on the error count, but it didn't seem to help, but the server has also been restarted a few times since then.

That won't help, but you can acknowledged the current number of errors so that you get a thumbs up SMART status on the dashboard, if the count continues to go up there's still a problem though, usually the SATA cable.

 

So far, so good.

1. MiniSAS cable replaced.
2. New 16TB drive put in to replace the parity drive in my primary server.
3. Old 16TB drive put into my backup server, precleared, then added as a second parity drive.  No new CRC errors, parity building.
4. My second new 16TB drive added to the primary server to expand storage space, taking place of an aging 4TB drive.
5. Data moved from three other 4TB drives onto the new drive and some data being moved from three other 16TB drives to balance them out a bit.

I then have one 4TB drive unused at the moment.  I plan to buy an external trayless enclosure to attach to my backup UnRaid server via 8088 cables, so that when drives are taken out of my primary, they help to expand the storage pool on my backup server.  I have a Pro license on my backup server and the Plus license on my primary server.  I'll upgrade it to Pro at some point, but I don't need to do that for a while.  I have 10 drives total in that server, so I have three 4TB drives to eventually replace and room for a couple more drives before I upgrade.  Growth beyond the 10 will probably be 2.5" SSDs.