INOVU DUAL DOCK QS V2 Manuel D'utilisation page 41

STEP 4: LEDs will flash sequentially, indicating the erasing is in progress. Each red LED refers
to 25% of erasing completion.
It is only when 25% of all HDD(s) is erased that the corresponding LED will remain constantly
on, leaving the other LED(s) in running stage.
When erasing operation is fully completed, all LEDs will flash regularly in red.
Note:
The percentage of erasing completion corresponds to the erasing of all sectors of the inserted
HDD(s). For example, total number of sectors for two 3To HDDs is the double of that for one
3To HDD, thus doubling the time it takes to observe the 4 LEDs erasing progress (every 25%).
Any time the erasing operation fails, LED on HDD2 flares in red, leaving the other LEDs off.
For more details, please refer to Section 7.4 & 7.5 of the "Erasing Mode Table Chart" under
"Diagnosis of LED" in below "NOTES" session.