Huawei OceanStor 9000 External Shared Mainly NFS and CIFS at the Moment

Huawei OceanStor 9000 external shared mainly NFS and CIFS at the moment. Set some parameters to improve performance of NFS mounted under the Linux operating system. Which of the following description is correct?

A) Rsize / wsize, read and write the maximum size of each block, it is recommended to adjust to the maximum. General Linux operating system environment, the maximum value of 1M.
B) Async, allowing asynchronous data write, synchronous write requirements. NFS server must brush each data into the hard disk before it can return success delay higher.
C) Noatime, if you do not need to record the file access time, you can increase this parameter to avoid frequent access, modify the access time to open pin.
D) Nolock, if there is a shared file between NFS clients, you can use this parameter. Reduce service-side file lock overhead.