To tune disk I/O performance for a non-SCSI disk, follow these steps:
Test the disk speed with this command:
/sbin/hdparm -t /dev/hdX
Enable direct memory access (DMA) with this command:
/sbin/hdparm -d1 /dev/hdX
Check the speed again using the hdparm command. Given that DMA is not enabled by default, the transfer rate might have improved considerably. In order to do this at every reboot, add the /sbin/hdparm -d1 /dev/hdX line to /etc/conf.d/local.start, /etc/init.d/rc.local, or whatever the startup script is called.