Patent ID: 10789134

Abstract:
A technique restores a file system of a storage input/output (I/O) stack to a deterministic point-in-time state in the event of failure (loss) of non-volatile random access memory (NVRAM) of a node. The technique enables restoration of the file system to a safepoint stored on storage devices, such solid state drives (SSD), of the node with minimum data and metadata loss. The safepoint is a point-in-time during execution of I/O requests (e.g., write operations) at which data and related metadata of the write operations prior to the point-in-time are safely persisted on SSD such that the metadata relating to an image of the file system on SSD (on-disk) is consistent and complete. Upon reboot after NVRAM loss, the technique identifies (i) the most recent safepoint, as well as (ii) the inflight writes that were persistently stored on disk after the most recent safepoint. The data and metadata of those inflight writes are then deleted to place the on-disk file system to its state at the most recent safepoint.