Spare block pool management in storage devices

A method for managing free super blocks in a storage device when a number of empty super blocks is at a critical level, the storage device comprises a controller to perform a method comprising:

• forming super blocks and storing information for empty super blocks in a free pool;
• determining that the storage device is initialized after a power failure;
• receiving a write request and identifying a source of the write request after the initialization of the storage device;
• identifying a client write request,
• determining that a criterion for creating a set of sub-super blocks exists;
• obtaining a first super block from the free pool and dividing the first super block into the set of sub-super blocks;
• allocating one of the sub-super blocks for the client write request;
• determining that the storage device has been reinitialized after a successive power failure;
• and
• closing an allocated sub-super block after the reinitialization of the storage device.

A method for recycling free super blocks in a storage device including super blocks and sub-super blocks, the storage device comprises a controller to perform a method comprising:

• determining that a recycling operation is to be performed;
• selecting a first super block for recycling, determining that the first super block is not mapped to a set of sub-super blocks in a mapping table, and performing garbage collection on the first super block;
• and
• selecting a second super block for recycling, determining that the second super block is mapped to the set of sub-super blocks in the mapping table, performing garbage collection on the set of sub-super blocks, and reuniting the set of sub-super blocks to reform the second super block.