Network-attached storage (NAS) is a centralized file-level (as opposed to block-level) external data storage server connected to a network providing data access to a heterogeneous group of clients such as Microsoft Windows, Apple, Macintosh, UNIX, and Linux platforms. NAS typically uses the existing network infrastructure based on IP and Ethernet. The management of the file system resides with the NAS storage system. With NAS, you can access data that might be stored across different platforms as if it were on your own computer. NAS can be used for public, private, and hybrid cloud storage for big data, virtual desktop infrastructure (VDI), high-performance computing (HPC), and so on. NAS systems contain one or more hard drives, often arranged into logical redundant storage containers or Redundant Array of Independent Disks (RAID).

NAS storage appliances provides terabytes of additional storage capacity, while providing automated, redundant data backups. Today’s NAS storage systems require minimal maintenance, reduce data storage costs, and provide fast file access from a centralized, secure data repository.

Figure 10-2 shows typical NAS server connectivity to a network infrastructure.

Figure 10-2 Typical NAS Server Connectivity

NAS supports two file- and data-sharing protocols—Common Internet File System (CIFS) and Network File System (NFS). CIFS is a version of the Server Message Block (SMB) protocol and was developed by Microsoft for Windows-based clients. SMB allows UNIX-based clients to access CIFS shared. CIFS and SMB are often used interchangeably because CIFS is a form of SMB. CIFS uses a client/server model where servers “share” and clients “use” or “map” the share. NFS was developed by Sun Microsystems for UNIX-based clients. Windows-based clients can also access NFS exports. NFS also uses a client/server model where servers “export” and clients “mount” the export. NFS is not compatible with CIFS/SMB; therefore, NFS clients cannot communicate directly with the SMB servers. However, UNIX and Linux clients can access CIFS shares by using SAMBA, which provides name resolution, file serving, and so on.

The top features to look for in an NAS storage appliance include

Redundant data backup: Ideally, one should be able to set up the NAS storage appliance as a RAID system. For example, in a RAID1 configuration, the same data is simultaneously stored on two hard drives. If one drive crashes, the data is still accessible from the second.

Fast data backup/restoration: For maximum performance, the NAS storage appliance should support the Gigabit Ethernet interface.

Lockability: For extra data security, most NAS storage appliances have a lockable front panel to prevent theft or tampering.

Small size and quiet operation: Some network storage appliances are small enough to fit on a shelf. Ideally, you should look for a quiet appliance that will not disturb nearby workers.

Support for Microsoft Distributed File System (MDFS): This feature allows you to map multiple storage devices, so users see them as one drive. Users do not have to remember which drive their data is stored on.