IN-FLIGHT BLOCK MAP FOR A CLUSTERED REDIRECT-ON-WRITE FILESYSTEM

A cluster server manages allocation of free blocks to cluster clients performing writes in a clustered file system. The cluster server manages free block allocation with a free block map and an in-flight block map. The free block map is a data structure or hardware structure with data that indicates blocks or extents of the clustered file system that can be allocated to a client for the client to write data. The in-flight block map is a data structure or hardware structure with data that indicates blocks that have been allocated to clients, but remain in-flight. A block remains in-flight until the clustered file system metadata has been updated to reflect a write performed to that block by a client. After a consistency snapshot of the metadata is published to the storage resources, the data at the block will be visible to other nodes of the cluster.