Network Attached Storage

August 29th, 2008
By Matt Gardenghi

Network Attached Storage consists of a set of hard drives usually in a RAID configuration and a specialized operating system configured to serve files at a high rate of speed. A file server differs from a NAS in one critical point. A traditional file server runs a standard OS (such as Linux, OS X or Windows). This server then has special file sharing software installed on it. Because it is a full OS and because the file serving capabilities are layered on top of the OS, there is a certain level of performance degradation. By contrast, a NAS has a specialized OS that is designed to perform one primary function: serve files quickly. The hardware and software are optimized to improve performance time. This performance increase becomes noticeable when a NAS has many simultaneous connections.

NAS systems typically serve files over Network File Share (NFS) and Server Message Block (SMB). Internally, the hard drives will usually be configured in a RAID setup. This can provide both an increase in data access speed (RAID 0) and/or redundancy (RAID 5). Both can be combined though doing so will increase the complexity thereby increasing the opportunity for configuration errors. Because the NAS shares files over a standard protocol and uses standard hard drives the open source community has created FreeNAS. As a result of this sort of “do-it-yourself” alternative, companies such as Novell, IBM, Sun, Network Appliance and others have differentiated themselves through their proprietary NAS OS and management interfaces. These interfaces will ease integration into existing identity management tools (LDAP, eDirectory, Active Directory) and often provide extra reporting capabilities.

NAS security primarily functions via access control lists. The administrator configures permissions (whether by group or individual) and grants read/write/delete access. The administrator could also choose to limit access to the NAS via virtual network segregation (VLAN or router rules) and physical separation.

Reference:
http://en.wikipedia.org/wiki/Network-attached_storage