Asus PS4 - Manual (Page 18)

Chapter 1: Product introduction 1-8
1.7.3 HDD status LED
SATAII/SAS HDD LED Description
HDD Status
LED
GREEN ON SATAII/SAS HDD power ON
RED* ON
HDD has failed and should be swapped
immediately
GREEN/
RED*
Blinking RAID rebuilding
HDD Activity
LED
GREEN Blinking Read/write data from/into the SATAII/SAS HDD
HDD status LED
HDD Activity LED
*The LED status functions only when you install the optional PIKE RAID card.