Pick your protocol: Multiprotocol file access in EMC Isilon OneFS

You’re rushing to meet a project deadline, and you need to update some related files that are stored on an EMC® Isilon® cluster. You’re working on a Linux computer, and you’re connected to the cluster over a Network File System (NFS) protocol. You need to access files in a directory that your coworker, who uses a Windows computer, created when they were connected to the same cluster over a Server Message Block (SMB) protocol. Thanks to the Isilon OneFS® operating system, you can seamlessly access your coworker’s files even though you are doing so through a very different protocol.

Multiple protocol support is a necessity in today’s IT organizations, which comprise a mix of Windows and UNIX/Linux operating environments. OneFS is designed to provide users with unified access to data on an Isilon cluster using a mix of common protocols, such as SMB, NFS, HTTP, and Hadoop Distributed File System (HDFS). For a full list of supported protocols, see the OneFS administration guides or “EMC Isilon Multiprotocol Data Access with a Unified Security Model”.

So how does OneFS support a multiprotocol environment? What are the steps a system administrator needs to take to set up multiprotocol access in OneFS?

We have two videos that cover the basics and provide recommendations for setting up multiprotocol access in OneFS. The first video, “File Access Basics in an Isilon OneFS Multi-Protocol Environments,” provides a whiteboard overview of this topic. The second video, “Technical Demo: Multi-Protocol File Access Using EMC Isilon OneFS,” provide a demonstration of common multiprotocol commands and tasks.

File access basics and AIMA in OneFS

Supporting a mix of protocols requires supporting a mix of user identities and file permissions. This requirement can leave system administrators with several considerations when configuring OneFS.

Before discussing how OneFS handles multiprotocol file access, let’s first review how two operating environments, Windows and UNIX/Linux, authorize access to files. In a Windows environment, users are identified based on unique security identifiers (SIDs). Files or directories are secured through an Access Control List (ACL). In an UNIX environment, users and groups are identified through user identifiers (UIDs) and group identifiers (GIDs), respectively. Files are secured using POSIX mode bits.

OneFS uses Authentication, Identity Management, and Authorization (AIMA) to assign the right permissions and identifiers to users (and groups) no matter which protocols they use to connect to the cluster. To securely support NFS and SMB clients, OneFS does three things:

  • Connects to directory services, such as Microsoft Active Directory (AD) and Lightweight Directory Access Protocol (LDAP), which provides a security database of user and group accounts along with their information
  • Authenticates users and groups
  • Controls access to directories and files

When a user connects to an Isilon cluster, OneFS scans Active Directory and LDAP for the user’s identifiers. Once the user is authenticated, OneFS creates an access token for the user. OneFS then maps the user’s account (known as “user mapping” in OneFS) in one directory service to another. This single access token is the key to authorizing the user so they can access files that are stored and created on the cluster using different protocols.

For example, if a user, Mike, accesses a file share through SMB, OneFS will scan Active Directory and find an SID for him. If OneFS does not find any UIDs or GIDs associated with Mike via LDAP, OneFS will generate a UID and GID for him and save them to Mike’s access token, so he can access files created by NFS users.

The same type of mapping occurs for file permissions. If a file was created through SMB, it will be assigned an ACL to control who can access the file. OneFS will create equivalent POSIX mode bits for this file. File permissions can be saved to the Isilon cluster on disk in one of three modes: native, UNIX, or SID. For more information about each mode, and about AIMA and user mapping, read the “Identities, Access Tokens, and the Isilon OneFS User Mapping Service” white paper.

This is a brief summary of how multiprotocol file access works in OneFS. Watch the following video, “File Access Basics in an Isilon OneFS Multi-Protocol Environments,” for more information and recommendations for configuring multiprotocol access in OneFS. In this video, Principal Solutions Architect Amol Choukekar answers the following frequently asked questions:

  • What are multiprotocol basics?
  • How do Window and UNIX clients differ when they access files on OneFS?
  • How does OneFS handle user and group identities?
  • How does OneFS store file permissions in a multiprotocol environment?
  • How do clients access files that were created using a different protocol?
  • How does OneFS manage file permissions?
  • What if user names are not similar across authentication providers?

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How to configure multiprotocol support in OneFS

You can manage user identity mapping and file permissions using the OneFS command-line interface and OneFS web administration interface. Watch the following video, “Technical Demo: Multi-Protocol File Access Using EMC Isilon OneFS” for demonstrations of the following tasks:

  • Review configured authentication providers
  • Review an access token for a user
  • Review existing identity mappings stored on the cluster
  • Delete existing identity mappings
  • Review ACL policies on the cluster
  • Create a user mapping rule for joining different user names

This video also offers the following demonstrations:

  • File access between Windows and UNIX
  • Creation of a synthetic ACL, which dynamically maps UNIX permissions to Windows rights
  • File permissions management

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For more information about implementing multiprotocol in OneFS, contact your account representative. If you have feedback about this blog or these videos, send an email to isi-knowledge@emc.com. If you have a request for new documentation, send an email to isicontent@emc.com.

About the Author: Kirsten Gantenbein

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