How /etc/exports works

About /etc/exports

The /etc/exports file contains a list of resources that can be exported. When rebooting, Data ONTAP executes the exportfs -a command in the /etc/rc file to automatically export all resources in /etc/exports file. As a result, you need not enter the exportfs command to export each resource.

In the /etc/exports file, you also specify the access restriction and security service with which clients can mount each resource. At any time after the filer is up and running, you can override any specification in the /etc/exports file with the exportfs command.

When changes to /etc/exports take effect

Entries in the /etc/exports file take effect when one of the following events happens:

Data ONTAP executes the exportfs -a command. This exports all entries in the /etc/exports file.
You enter the exportfs command followed by a path name specified in the /etc/exports file. This exports the specified entry.

For more information about how to use the exportfs command, see Exporting or unexporting resources using the exportfs command.

Targets to which you export a resource

You can specify in the /etc/exports file to export a resource to these targets:

Hosts
Netgroups
Subnets

Information in /etc/exports

The /etc/exports file specifies the following types of information:

Complete path name of each resource to be exported.
Targets to which each resource is exported. Targets are optional.
Access restrictions with which each resource can be mounted. Access restrictions are optional.
Security service each resource uses. Security services are optional.

Rules for specifying an /etc/exports entry

The following rules determine how a resource is exported:

If the /etc/exports file entry contains only the path name of a resource, that resource can be mounted read-write by all hosts.
If the /etc/exports file entry contains the path name of a resource followed by options, the resource is exported with access restrictions, which determine
- Which targets have permission to mount the resource.
- The type of access allowed for each target (for example, read-only or read-write).
- How NFS requests made by root on the client are handled. The requests can be denied, allowed, or allowed with a converted UID.
In an /etc/exports file entry, the first access restriction option is preceded by a dash (-). Subsequent options are preceded by a comma (,).

Example

/vol/vol0 -access=host1:host2,root=host1,rw=host2

The steps for exporting a resource from the /etc/exports file vary with the type of target to which you export the resource.

Limitation of the /etc/exports file

Each line of the /etc/exports file can contain up to 1,024 characters.

For detailed information

The following sections describe how different options in the /etc/exports file control the ways resources are exported: