PowerScale OneFS Web Administration Guide

Data access control overview

OneFS supports two types of permissions data on files and directories that control who has access: Windows-style access control lists (ACLs) and POSIX mode bits (UNIX permissions). You can configure global policy settings that enable you to customize default ACL and UNIX permissions to best support your environment.

The OneFS file system installs with UNIX permissions as the default. You can give a file or directory an ACL by using Windows Explorer or OneFS administrative tools. Typically, files created over SMB or in a directory that has an ACL, receive an ACL. If a file receives an ACL, OneFS stops enforcing the file's mode bits; the mode bits are provided for only protocol compatibility, not for access control.

OneFS supports multiprotocol data access over Network File System (NFS) and Server Message Block (SMB) with a unified security model. A user is granted or denied the same access to a file when using SMB for Windows file sharing as when using NFS for UNIX file sharing.

NFS enables Linux and UNIX clients to remotely mount any subdirectory, including subdirectories created by Windows or SMB users. Linux and UNIX clients also can mount ACL-protected subdirectories created by a OneFS administrator. SMB provides Windows users access to files, directories and other file system resources stored by UNIX and Linux systems. In addition to Windows users, ACLs can affect local, NIS, and LDAP users.

By default, OneFS maintains the same file permissions regardless of the client’s operating system, the user’s identity management system, or the file sharing protocol. When OneFS must transform a file’s permissions from ACLs to mode bits or vice versa, it merges the permissions into an optimal representation that uniquely balances user expectations and file security.