Standard block devices provide atomicity of the device sector size. The Fusion ioMemory card support atomic write I/O which provides atomicity for an I/O operation, even if it spans sectors of the device. Atomic write I/O ensures that all the blocks that are mentioned in the operation are written successfully on the device, or none of the blocks are written. Symantec leverages this capability of Fusion ioMemory card for Veritas file systems and volumes.