Asus KFN5-Q/SAS - Manual (Page 117)

5-10 Chapter 5: RAID configuration
For server systems, we recommend using a lower array block size. For
multimedia computer systems used mainly for audio and video editing,
we recommend a higher array block size for optimum performance.
4. Use the up or down arrow keys to select the stripe block size
appropriate to your drive usage, then press <Enter>.
The available stripe size values range from 8KB to 128KB. The default
stripe size is Optimal. You must choose the stripe size value based on
the projected drive usage. For low disk usage, select 8KB/16KB. For
typical disk usage, select 64KB. Select 128KB for performance disk
usage.
5. Press <TAB> to move to the Free Disks section.
6. Highlight the hard disk drives that you want to add in the RAID set,
then press the right arrow key to select. The selected hard disk drives
appear in the Array Disks section. Repeat the process until all desired
hard disk drives are added. RAID 5 requires three to six hard disk
drives.