No subject

May 15 15:53:37 backup_a kernel: ad6: TIMEOUT - READ_DMA retrying (1  
retry left) LBA=49814018
May 15 15:53:38 backup_a kernel: ad6: WARNING - READ_DMA soft error  
(ECC corrected) LBA=49871650
May 15 15:53:38 backup_a kernel: ad6: WARNING - READ_DMA UDMA ICRC  
error (retrying request) LBA=49871682
May 15 15:53:38 backup_a kernel: ad6: timeout waiting to issue command
May 15 15:53:38 backup_a kernel: ad6: error issuing READ_DMA command
May 15 15:53:39 backup_a kernel: ad6: WARNING - READ_DMA UDMA ICRC  
error (retrying request) LBA=49871682
May 15 15:53:39 backup_a kernel: ad6: FAILURE - READ_DMA  
status=5<CORRECTABLE,ERROR>  
error=61<UNCORRECTABLE,MEDIA_CHANGED,ILLEGAL_LENGTH> LBA=49871682
May 15 15:53:39 backup_a kernel: ad6: WARNING - READ_DMA soft error  
(ECC corrected) LBA=12671810
May 15 15:53:39 backup_a kernel: ad6: WARNING - READ_DMA soft error  
(ECC corrected) LBA=12671842
May 15 15:53:39 backup_a kernel: ad6: WARNING - READ_DMA soft error  
(ECC corrected) LBA=12671906
May 15 15:55:42 backup_a syslogd: kernel boot file is /boot/kernel
May 15 15:55:42 backup_a kernel: ad6: FAILURE - device detached
May 15 15:55:42 backup_a kernel: subdisk6: detached
May 15 15:55:42 backup_a kernel: ad6: detached

Does this mean the controller is reporting the disk is gone?

Dylan
I got similar messages using two disks with an old WD sata disk (among  
the first 250 GB disks I think) and nata during boot. Sometimes the  
disk attached, but mostly not. It attached ok in OpenBSD and NetBSD  
but it took quite some time there to get done (error handling?).

However, as far as I can remember, it worked ok in DragonFly as long  
as it attached during boot. I don't think came up with a good  
solution. Using a different disk or an AHCI controller is probably  
easiest ;-)

Keep digging though,
Max