What is a file area network (FAN)?

A File Area Network (FAN) is a network that is connected to a file server or network attached storage(NAS) or storage area network (SAN)for the purpose of sharing files. It’s the combination of a tiered storage model, a storage admission tier (SAT), and a NAS or SAN. The SAT employs storage virtualization to separate logical file access form physical file locations, which offers several advantages such as centralized management, deployment over heterogeneous hardware, and flexible file portability.

The controls of a file area network pervade the entire organization and provide control over all of the file information. File attributes, metadata, and content values are managed regardless of platform. A FAN can also establish file visibility based on user permissions and conduct non-disruptive file migrations.

These are the elements of a mature FAN:

1. Storage Devices
2. Namespaces
3. File-serving Devices and Interfaces
4. File Optimization Services
5. File Management Services
6. File Security Services
7. Connectivity
8. End Clients

File Virtualization
FANs greatly simplify network file management (NFM) with file virtualization There are two methods of file virtualization: built-in and standalone. The first method has virtualization built into the NAS (Network Attached Storage) or storage system, creating a ‘global’ file system. This file system manages the metadata, such as file stubs, for file locations. A disadvantage of this method is that it locks you in to the hardware you’re currently using because the metadata is exclusive to the users of the file system. To expand these systems, you will typically have to buy hardware from the same vendor, so you give up your ability to mix various brands of hardware. Global file systems also don’t have file-level granularity in many cases.

The other method for file virtualization employs a standalone virtualization engine or appliance. These engines can be located within the data path (in-band) or outside of the data path (out-of-band). In-band engines often have better performance, but out-of-band engines are easier to set up. Standalone solutions move files based on attribute related policies and have file-level granularity. They also allow you to use any combination of hardware.

File virtualization also enables the creation of tiered storage, which is a primary component of FANs. The ability to move data between tiered NAS/network file servers allows files to be moved into more appropriate systems based on how frequently they are accessed. This can minimize overhead and operational costs. Accessing older data in a tiered storage system is also much easier to manage with file virtualization because there’s no need to create and keep track of a stub file to access the data.