Solid state device write operation management system

摘要

A solid state device (SSD) write operation management system including a file system that incorporates SSD status information into its operational logic is disclosed. By incorporating SSD status information, the system achieves various advantages over conventional systems, such as enhanced write performance and extended SSD lifespan. The system processes various criteria to select the optimal virtual device (“vdev”) for data allocation in response to a write request. The first criterion utilizes Program/Erase counts of physical blocks contained in the SSDs. Another criterion is the number of physical free blocks of a drive. If the average of the selected vdev's physical free blocks is higher than the OP threshold, then the system selects for data allocation the vdev with the greatest amount of logical free space. In the instance that the average is lower, the system schedules garbage collection for the vdev.

主权项

1. A method for processing a write operation for a solid-state drive (SSD) having solid-state memory, the method comprising:
determining one or more vdevs that have not exceeded an End of Life threshold, wherein the one or more vdevs that have not exceeded an End of Life threshold comprise a queue of vdevs; determining a Program/Erase (P/E) count and an average physical free space for each vdev from the queue of vdevs; identifying among the P/E counts a maximum P/E count and a minimum P/E count; determining a difference in value between the maximum P/E count and minimum P/E count; where the determined difference is greater than a P/E count threshold and the vdev with the minimum P/E count possesses sufficient logical free space for the write operation,
performing the write operation on the vdev from the queue of vdevs with the minimum P/E count; and where the determined difference is less than or equal to the P/E count threshold,
selecting a vdev from the beginning of the queue of vdevs;where the average physical free space of the selected vdev is below an over-provisioning threshold,
(a) electing the first available vdev from the queue that possesses a garbage collection wait timer whose value is zero,(b) where the average physical free space of the elected vdev is below the over-provisioning threshold,
initiating a garbage collection procedure on the elected logical device,(c) where the average physical free space of the elected vdev is above the over-provisioning threshold,
performing the write operation on the elected vdev, andrepeating (a), (b), and (c) until an elected vdev is above the over-provisioning threshold.