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Amazon Elastic File System
User Guide

Unsupported NFSv4 Features

While Amazon Elastic File System does not support NFSv2, or NFSv3, Amazon EFS supports both NFSv4.1 and NFSv4.0, except for the following features:

  • pNFS

  • Client delegation or callbacks of any type

    • Operation OPEN always returns OPEN_DELEGATE_NONE as the delegation type.

    • The operation OPEN returns NFSERR_NOTSUPP for the CLAIM_DELEGATE_CUR and CLAIM_DELEGATE_PREV claim types.

  • Mandatory locking

    All locks in Amazon EFS are advisory, which means that READ and WRITE operations do not check for conflicting locks before the operation is executed.

  • Deny share

    NFS supports the concept of a share deny, primarily used by Windows clients for users to deny others access to a particular file that has been opened. Amazon EFS does not support this, and returns the NFS error NFS4ERR_NOTSUPP for any OPEN commands specifying a share deny value other than OPEN4_SHARE_DENY_NONE. Linux NFS clients do not use anything other than OPEN4_SHARE_DENY_NONE.

  • Access control lists (ACL)

  • Amazon EFS does not update the time_access attribute on file reads. Amazon EFS updates time_access in the following events:

    • When a file is created (an inode is created).

    • When NFS client makes an explicit setattr call.

    • On a write to the inode caused by, for example, file size changes or file metadata changes.

    • Any inode attribute is updated.

  • Namespaces

  • Persistent reply cache

  • Kerberos based security

  • NFSv4.1 data retention

  • SetUID on directories

  • Unsupported file types when using the CREATE operation: Block devices (NF4BLK), character devices (NF4CHR), attribute directory (NF4ATTRDIR), and named attribute (NF4NAMEDATTR).

  • Unsupported attributes: FATTR4_ARCHIVE, FATTR4_FILES_AVAIL, FATTR4_FILES_FREE, FATTR4_FILES_TOTAL, FATTR4_FS_LOCATIONS, FATTR4_MIMETYPE, FATTR4_QUOTA_AVAIL_HARD, FATTR4_QUOTA_AVAIL_SOFT, FATTR4_QUOTA_USED, FATTR4_TIME_BACKUP, and FATTR4_ACL.

    An attempt to set these attributes will result in an NFS4ERR_ATTRNOTSUPP error that is sent back to the client.