Increase scsi timeouts in Linux

# First, check your current settings and jot them down somewhere:
for a in /sys/class/scsi_generic/*/device/timeout; do echo -n "$a "; cat "$a" ; done;

# Here's how to increase the timeout across all devices to 180 seconds:
for i in /sys/class/scsi_generic/*/device/timeout; do echo 180 > "$i"; done

# After boot, that'll go away, so make it persistant:
echo 'for i in /sys/class/scsi_generic/*/device/timeout; do echo 180 > "$i"; done' >> /etc/rc.local

# Use this command again to check the values:
for a in /sys/class/scsi_generic/*/device/timeout; do echo -n "$a "; cat "$a" ; done;