Over-provisioning

Over-provisioning (OP) is to reserve additional capacity from a SSD usable capacity.  The higher OP means the users data capacity becomes smaller.

When a certain percentage of an SSD’s space has been reserved as OP, it helps extend the lifetime, endurance, and overall performance of the drive itself. It does so by providing a permanent “swap space” for the drive’s controller to manage all the data traffic and storage for the drive.

OP benefits would include better Garbage Collection, lower Power Consumption, better performance, and lifespan. It increases more free blocks to temporarily store data while erasing blocks of invalid data. Additionally, OP gives controllers extra free space needed to move data and results in faster execution. Secondly, SSD controllers can operate quickly, resulting in less power from devices to complete tasks. OP can also offer the flash controller extra buffer space for managing P/E cycles and ensuring a write operation will have immediate access to a pre-erased block. So, overprovisioning increases SSD performance and makes SSDs work smartly.

Apart from being used to store Controller firmware, optimized GC, and wear-leveling (WL), OP is a space designated as Spare Block. After certain usage duration of SSD, these Spare Blocks result in Bad Block. The reserved Block in OP space can be swapped with LBB to alleviate the wear and loss during the NAND Flash life cycle, as well as maintain performance level of the SSD.