Verification of data coherency in word-addressable files that support concurrent access

A method and apparatus for testing data coherency in a file system implemented on a data processing arrangement. A record of file addresses is maintained for addresses that are not targeted by write operations, and word address ranges for write operations are selected from the record of file addresses not targeted by other write operations. A plurality of asynchronous write operations that specify word address ranges and data to be written are issued. For each completed write operation, an asynchronous read operation that references the address range of the completed write operation is issued. The data returned from the read operation is verified against data issued in the completed write operation. The record of file addresses not targeted by write operations is updated when the verifying step is complete.