Use something like this on boot to check that all your SCSI devices either support Error Recovery Control at 7 seconds, or else have a large enough SCSI layer timeout to prevent them being kicked from a RAID array on bad sector reads.

fix-disk-timeouts

#!/bin/sh

for disk in `find /sys/block -maxdepth 1 -name 'sd*' | xargs -n 1 basename`
do
    smartctl -q errorsonly -l scterc,70,70 /dev/${disk}

    if test $? -eq 4
    then
        echo "/dev/${disk} doesn't support scterc, setting timeout to 180s /o\\"
        echo 180 > /sys/block/${disk}/device/timeout
    else
        echo "/dev/${disk} supports scterc \\o/"
    fi
done