"currently unreadable sectors" message

[RoadHazard]

What is this message telling me?

Device: /dev/ada1, 8 Currently unreadable (pending) sectors
Device: /dev/ada1, 8 Offline uncorrectable sectors

Nothing good, methinks.

 

[bigphil]

That is a SMART alert telling you that its about time to replace that disk! Before shutting down or rebooting, from a shell you can run "smartctl -i /dev/ada1" to get the serial number from the drive so you know which to replace. Look at the FreeNAS guide for help on how to replace the disk.

 

[Robert Trevellyan]

Take a look at this:
https://forums.freenas.org/index.php?resources/hard-drive-troubleshooting-guide.17/

 

[RoadHazard]

Thanks for the pointers. The SMART test confirms that some sectors are failing on one disk. Specifically, ID 197 and 198 both show 8 bad sectors. From what I understand, that's an unrecoverable error and grounds for replacing the disk.

It so happens that my disks are all Seagate ST3000DM001 drives, which seem to have a reputation for poor reliability. Should I replace the failing drive with an identical make/model (although obviously a new one), or a completely different type of drive but with similar capacity? I know FreeNAS tolerates pools of mismatched drives, but what does the Hive Mind recommend?

 

[Robert Trevellyan]

Should I replace the failing drive with an identical make/model

I'd pick any NAS drive of equal or greater capacity (WD Red, Seagate IronWolf, HGST NAS etc).

 

[RoadHazard]

Done!

I bought a WD drive of the same capacity, followed the instructions in section 8.1.10 of the FreeNAS User Guide, and the resilver is now underway. The whole process was remarkably smooth and my system was only down for about 20 minutes. I should do this more often! ;-)