Thanks, that should be easy to tell. The disk activity light on it is on solid.
Here's what I have now.
And here's a bit of the messages log file.
Jul 28 20:54:13 freenas Trying to mount root from zfs:freenas-boot/ROOT/11.3-U3.2 []...
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): READ_FPDMA_QUEUED. ACB: 60 01 af f4 a0 40 ba 02 00 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): CAM status: ATA Status Error
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): ATA status: 41 (DRDY ERR), error: 40 (UNC )
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): RES: 41 40 af f4 a0 00 ba 02 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): Retrying command
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): READ_FPDMA_QUEUED. ACB: 60 01 af f4 a0 40 ba 02 00 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): CAM status: ATA Status Error
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): ATA status: 41 (DRDY ERR), error: 40 (UNC )
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): RES: 41 40 af f4 a0 00 ba 02 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): Retrying command
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): READ_FPDMA_QUEUED. ACB: 60 01 af f4 a0 40 ba 02 00 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): CAM status: ATA Status Error
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): ATA status: 41 (DRDY ERR), error: 40 (UNC )
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): RES: 41 40 af f4 a0 00 ba 02 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): Retrying command
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): READ_FPDMA_QUEUED. ACB: 60 01 af f4 a0 40 ba 02 00 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): CAM status: ATA Status Error
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): ATA status: 41 (DRDY ERR), error: 40 (UNC )
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): RES: 41 40 af f4 a0 00 ba 02 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): Retrying command
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): READ_FPDMA_QUEUED. ACB: 60 01 af f4 a0 40 ba 02 00 00 00 00
......
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): Error 5, Retries exhausted
Jul 28 20:54:13 freenas GEOM: ada1: the secondary GPT table is corrupt or invalid.
Jul 28 20:54:13 freenas GEOM: ada1: using the primary only -- recovery suggested.
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): READ_FPDMA_QUEUED. ACB: 60 01 40 00 00 40 00 00 00 00 00 00
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): CAM status: ATA Status Error
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): ATA status: 41 (DRDY ERR), error: 40 (UNC )
Jul 28 20:54:13 freenas (ada1:ahcich10:0:0:0): RES: 41 40 40 00 00 00 00 00 00 00 00
Still going to swap the two caddies, but from the looks of the log, it knows that ada1 is there.
Hold on.....