AWS SDK Version 3 for .NET
API Reference

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Creates a mount target for a file system. You can then mount the file system on EC2 instances via the mount target.

You can create one mount target in each Availability Zone in your VPC. All EC2 instances in a VPC within a given Availability Zone share a single mount target for a given file system. If you have multiple subnets in an Availability Zone, you create a mount target in one of the subnets. EC2 instances do not need to be in the same subnet as the mount target in order to access their file system. For more information, see Amazon EFS: How it Works.

In the request, you also specify a file system ID for which you are creating the mount target and the file system's lifecycle state must be available. For more information, see DescribeFileSystems.

In the request, you also provide a subnet ID, which determines the following:

After creating the mount target, Amazon EFS returns a response that includes, a MountTargetId and an IpAddress. You use this IP address when mounting the file system in an EC2 instance. You can also use the mount target's DNS name when mounting the file system. The EC2 instance on which you mount the file system via the mount target can resolve the mount target's DNS name to its IP address. For more information, see How it Works: Implementation Overview.

Note that you can create mount targets for a file system in only one VPC, and there can be only one mount target per Availability Zone. That is, if the file system already has one or more mount targets created for it, the subnet specified in the request to add another mount target must meet the following requirements:

If the request satisfies the requirements, Amazon EFS does the following:

The CreateMountTarget call returns only after creating the network interface, but while the mount target state is still creating, you can check the mount target creation status by calling the DescribeMountTargets operation, which among other things returns the mount target state.

We recommend you create a mount target in each of the Availability Zones. There are cost considerations for using a file system in an Availability Zone through a mount target created in another Availability Zone. For more information, see Amazon EFS. In addition, by always using a mount target local to the instance's Availability Zone, you eliminate a partial failure scenario. If the Availability Zone in which your mount target is created goes down, then you won't be able to access your file system through that mount target.

This operation requires permissions for the following action on the file system:

This operation also requires permissions for the following Amazon EC2 actions:


For .NET Core and PCL this operation is only available in asynchronous form. Please refer to CreateMountTargetAsync.

Namespace: Amazon.ElasticFileSystem
Assembly: AWSSDK.ElasticFileSystem.dll
Version: 3.x.y.z


public virtual CreateMountTargetResponse CreateMountTarget(
         CreateMountTargetRequest request
Type: Amazon.ElasticFileSystem.Model.CreateMountTargetRequest

Container for the necessary parameters to execute the CreateMountTarget service method.

Return Value
The response from the CreateMountTarget service method, as returned by ElasticFileSystem.


BadRequestException Returned if the request is malformed or contains an error such as an invalid parameter value or a missing required parameter.
FileSystemNotFoundException Returned if the specified FileSystemId value doesn't exist in the requester's AWS account.
IncorrectFileSystemLifeCycleStateException Returned if the file system's lifecycle state is not "available".
InternalServerErrorException Returned if an error occurred on the server side.
IpAddressInUseException Returned if the request specified an IpAddress that is already in use in the subnet.
MountTargetConflictException Returned if the mount target would violate one of the specified restrictions based on the file system's existing mount targets.
NetworkInterfaceLimitExceededException The calling account has reached the limit for elastic network interfaces for the specific AWS Region. The client should try to delete some elastic network interfaces or get the account limit raised. For more information, see Amazon VPC Limits in the Amazon VPC User Guide (see the Network interfaces per VPC entry in the table).
NoFreeAddressesInSubnetException Returned if IpAddress was not specified in the request and there are no free IP addresses in the subnet.
SecurityGroupLimitExceededException Returned if the size of SecurityGroups specified in the request is greater than five.
SecurityGroupNotFoundException Returned if one of the specified security groups doesn't exist in the subnet's VPC.
SubnetNotFoundException Returned if there is no subnet with ID SubnetId provided in the request.


This operation creates a new mount target for an EFS file system.

To create a new mount target

var response = client.CreateMountTarget(new CreateMountTargetRequest 
    FileSystemId = "fs-01234567",
    SubnetId = "subnet-1234abcd"

string fileSystemId = response.FileSystemId;
string ipAddress = response.IpAddress;
string lifeCycleState = response.LifeCycleState;
string mountTargetId = response.MountTargetId;
string networkInterfaceId = response.NetworkInterfaceId;
string ownerId = response.OwnerId;
string subnetId = response.SubnetId;


Version Information

.NET Framework:
Supported in: 4.5, 4.0, 3.5

Portable Class Library:
Supported in: Windows Store Apps
Supported in: Windows Phone 8.1
Supported in: Xamarin Android
Supported in: Xamarin iOS (Unified)
Supported in: Xamarin.Forms

See Also