Preclear stalled

[nraygun]

I popped in a 2TB drive (WD Green) to use as a backup drive and started the preclear on it last night.

When I checked it this morning, it was in a "stalled" state. The log shows this:

Jun 20 06:51:02 preclear_disk_WD-XXX: Zeroing: progress - 90% zeroed
Jun 20 07:06:08 preclear_disk_WD-XXX: smartctl exec_time: 1s
Jun 20 07:20:02 preclear_disk_WD-XXX: Zeroing: progress - 95% zeroed
Jun 20 07:53:26 preclear_disk_WD-XXX: smartctl exec_time: 10s
Jun 20 07:53:37 preclear_disk_WD-XXX: smartctl exec_time: 21s
Jun 20 07:53:47 preclear_disk_WD-XXX: smartctl exec_time: 31s
Jun 20 07:53:47 preclear_disk_WD-XXX: dd[30448]: Pausing (smartctl exec time: 31s)
Jun 20 07:53:57 preclear_disk_WD-XXX: smartctl exec_time: 41s
Jun 20 07:54:08 preclear_disk_WD-XXX: smartctl exec_time: 52s
Jun 20 07:54:18 preclear_disk_WD-XXX: smartctl exec_time: 62s
Jun 20 07:54:18 preclear_disk_WD-XXX: killing smartctl with pid 30816 - probably stalled...

Any ideas what went wrong here?

I just hit continue and it looks like it's on the post-read task.