# Mount settings used by EFS mount helper
<a name="mount-helper-setting"></a>

The Amazon EFS mount helper client uses the following mount options that are optimized for Amazon EFS:
+ `nfsvers=4.1` – used when mounting on EC2 Linux instances

  `nfsvers=4.0` – used when mounting on supported EC2 Mac instances running macOS Big Sur, Monterey, and Ventura
+ `rsize=1048576` – Sets the maximum number of bytes of data that the NFS client can receive for each network READ request to 1048576, the largest available, to avoid diminished performance.
+ `wsize=1048576` – Sets the maximum number of bytes of data that the NFS client can send for each network WRITE request to `1048576`, the largest available, to avoid diminished performance.
+ `hard` – Sets the recovery behavior of the NFS client after an NFS request times out, so that NFS requests are retried indefinitely until the server replies, to ensure data integrity.
+ `timeo=600` – Sets the timeout value that the NFS client uses to wait for a response before it retries an NFS request to 600 deciseconds (60 seconds) to avoid diminished performance.
+ `retrans=2` – Sets to 2 the number of times the NFS client retries a request before it attempts further recovery action.
+ `noresvport` – Tells the NFS client to use a new non-privileged Transmission Control Protocol (TCP) source port when a network connection is reestablished. Using the `noresvport` option helps to ensure that your EFS file system has uninterrupted availability after a reconnection or network recovery event.
+ `mountport=2049` – only used when mounting on EC2 Mac instances running macOS Big Sur, Monterey, and Ventura.