ad0: 114473MB <ST3120023A> [232581/16/63] at ata0-master UDMA33
ad2: 176700MB <IC35L180AVV207-1> [359010/16/63] at ata1-master UDMA33
ad3: 157066MB <HDS722516VLAT80> [319120/16/63] at ata1-slave UDMA33

sysinstall の Post configuration -> Fdisk ad3 に User Entire Disk 指定で ad3s1 を作成 Disklabel で ad3s1d を作成(自動で newfs -U -O1 /dev/ad3s1d が動き出す)

yoya@alt% mv: /home2/yoya/anim/wanda.rar: Input/output error

yoya@alt% dmesg
	＜略＞
ad0: hard error cmd=read fsbn 93486016 of 46743008-46743135
 trying PIO mode
ad0: DMA problem fallback to PIO mode
ad0: DMA problem fallback to PIO mode

危険か…