Network Attached Storage (NAS)
Network Attached Storage (NAS) is a storage system that is set up with its own network address. The NAS device is connected to a local area network.
We would like to limit the term NAS to systems where the need to maintain and manage a traditional operating system has been removed in some regards. Management is easy thanks to a simplified GUI. The primary protocols that clients use to communicate with NAS servers are CIFS and NFS, but in some cases protocols such as FTP and HTTP may be involved. A NAS system that supports both CIFS and NFS should be able to allow data sharing between various clients, and to support this it should have some kind of user or file permission mapping.
Why?
If we compare SAN and NAS, one of the primary differences is in where the file system resides. In the case of NAS, the file system resides on the NAS server, while for SAN every client has its own file system. While this seems to be a trivial difference, it enables the NAS system to make snapshots without client integration and also allows for easy file system management such as growing and shrinking the file system.
While a SAN system removes the need to attach individual disks to each client, there is still storage partitioning. In a SAN environment, growing and shrinking the file system may pose a challenge.
With a NAS system, we remove the partitioning. We also benefit from the fact that we can share data between different operating systems. Depending on the functionality of the NAS system, we might even benefit from more disk spindles to spread the load.
Since CIFS and NFS are integrated into the client operating system, there is no need for extra software and hardware apart from the regular network connection.
One of the biggest benefits of a NAS system is simple and quick snapshot-based backup, along with the option of cloning the logical volumes to permit space-efficient testing and development. One other use for NAS for application storage is in massive computer farms, where you have several hundred or even thousands of computers connected to a common storage solution to permit data sharing.
Further reasons for implementing a NAS solution:
- Option of consolidating traditional fileservers
- Simplification of management
- NAS combined with block-based replication resolves backup issues in enterprise solutions
- Storage of application data where data needs to be shared
- Easier to implement than SAN