I have LVM setup with four disks, three WD 320GB and one samsung 500GB, and I've come to believe one of these disks has gone bad because fsck on the virtual device always chrashes my machine, makes it freeze somehow.

Before freezing, it always spews out some errors about ATA4.00, which I believe is on of the aforementioned disks. I have also found some similar errors related to NCQ https://bugs.launchpad.net/ubuntu/+s...22/+bug/147858 and was wondering how to confirm this, and if it is NCQ error, what to do next. If it is a bad disk, I need to know how to find what physical device ATA4.00 refers to (aka /dev/sdX or something) so I can remove this from the array.

Thanks in advance

Edit: some of the errors in /var/log/messages regarding ata4.00
Code:
Dec 23 02:00:22 Xeon kernel: [49341.728857] ata4: soft resetting port
Dec 23 02:00:23 Xeon kernel: [49341.884622] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
Dec 23 02:00:23 Xeon kernel: [49341.925041] ata4.00: configured for UDMA/133
Dec 23 02:00:23 Xeon kernel: [49341.925056] ata4: EH complete
Dec 23 02:00:23 Xeon kernel: [49342.351836] ata4: soft resetting port
Dec 23 02:00:23 Xeon kernel: [49342.507578] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
Dec 23 02:00:23 Xeon kernel: [49342.555955] ata4.00: configured for UDMA/133
Dec 23 02:00:23 Xeon kernel: [49342.555967] ata4: EH complete
Dec 23 02:00:32 Xeon kernel: [49350.889596] ata4: soft resetting port
Dec 23 02:00:32 Xeon kernel: [49351.045356] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
Dec 23 02:00:32 Xeon kernel: [49351.093753] ata4.00: configured for UDMA/133
Dec 23 02:00:32 Xeon kernel: [49351.093765] ata4: EH complete
Dec 23 02:00:32 Xeon kernel: [49351.132169] ata4.00: limiting speed to UDMA/100:PIO4
Dec 23 02:00:32 Xeon kernel: [49351.440674] ata4: soft resetting port
Dec 23 02:00:32 Xeon kernel: [49351.596437] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
Dec 23 02:00:32 Xeon kernel: [49351.640908] ata4.00: configured for UDMA/100
Dec 23 02:00:32 Xeon kernel: [49351.640920] ata4: EH complete