SSD auxiliary battery power for handling ungraceful shutdown with host

A host device, comprising:

• a memory;
• a redundant array of independent disks (RAID) controller coupled to the memory;
• a host power management circuit coupled to the memory and the RAID controller;
• and
• a rechargeable battery coupled to the host power management circuit;
• wherein the host power management circuit is configured to supply power from the rechargeable battery to a storage device, and the RAID controller is configured to receive a message from the storage device indicating a detected loss in the supplied power, and to supply emergency power to the storage device in response to the message, wherein the storage device controller is configured to determine an optimal amount of emergency power and time required to write data to the memory.

A redundant array of independent disks (RAID) system, comprising:

• a plurality of storage devices, each of the storage devices including:
• a non-volatile memory;
• a storage device controller coupled to the memory;
• a storage device power management circuit coupled to the non-volatile memory and the storage device controller;
• and
• a rechargeable battery coupled to the storage device power management circuit;
• and
• a host device coupled to the storage devices, the host device including:
• a memory;
• a RAID controller coupled to the memory;
• and
• a host power management circuit coupled to the memory and the RAID controller;
• wherein each of the storage device controllers is configured to receive supplied power from the host power management circuit;
• and
• wherein the storage device power management circuit of one of the storage devices is configured to detect a loss in the supplied power, to cause the storage device controller of the one of the storage devices to send a message to the host device indicating the loss in power, and to receive emergency power from the host device or the RAID controller in response to the message, wherein the storage device controller is configured to determine an optimal amount of emergency power and time required to write data to the memory.