DFS is a requirement for use in Clustering setup. See Clustering for an overview of the feature. 

What it is meant for

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As the binarydata handler, create a new Flysystem local adater adapter configured to read/write to the NFS mount point on each local server. As metadata handler handler, create a dfs one, configured with a doctrine connection. We recommend that a dedicated database is used for DFS metadata. In our example, we will use one named dfs. 

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If you decide to change this setting, make sure you also set io.url_prefix to a matching value. If you set the NFS adapter's directory to "/path/to/nfs/storage", use this configuration so that the files can be served by symfonySymfony:

exponential:
	system:
		default:
			io:
				url_prefix: "storage"

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Web server rewrite rules.

The default eZ Publish Platform rewrite rules will let image requests be served directly from disk. With native support, files matching ^/var/([^/]+/)?storage/images(-versioned)?/.* have to be passed through /web/app.php.

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