Power-loss protection for address conversion table using a charged capacitor in a storage device

A control method for a storage device, the storage device including a non-volatile memory, a controller configured to control the non-volatile memory, a volatile memory, a power supply circuit configured to generate a power supply voltage using power supplied from an external power supply, and a capacitor, said control method comprising:

• periodically storing a hierarchical logical-to-physical address conversion table residing in the volatile memory into the non-volatile memory during normal operations, the hierarchical logical-to-physical address conversion table including an intermediate table and a lower table;
• detecting a power loss event;
• in response to the power loss event, storing first data residing in the volatile memory into the non-volatile memory using the capacitor as a backup power supply, the first data including change logs of the lower table;
• determining after storing the first data whether an amount of charge remaining in the capacitor is sufficient to store second data residing in the volatile memory into the non-volatile memory, the second data including the intermediate table;
• determining that the amount of charge remaining in the capacitor after storing the first data is sufficient to store the second data residing in the volatile memory into the non-volatile memory;
• storing the second data residing in the volatile memory into the non-volatile memory;
• determining after storing the second data whether an amount of charge remaining in the capacitor is sufficient to store third data residing in the volatile memory into the non-volatile memory, the third data including the lower table;
• storing the third data residing in the volatile memory into the non-volatile memory only if the amount of charge remaining in the capacitor after storing the second data is sufficient to store the third data residing in the volatile memory into the non-volatile memory;
• and
• after recovering from the power loss event,
• restoring the intermediate table in the volatile memory using the intermediate table stored in the non-volatile memory during normal operations or using the second data which was stored into the non-volatile memory in response to the power loss event, and
• restoring the lower table in the volatile memory using the lower table stored in the non-volatile memory during normal operations or using the lower table stored in the non-volatile memory during normal operations and the change logs of the lower table included in the first data which was stored into the non-volatile memory in response to the power loss event.