Network-Attached Secure Disks (NASD) is 1997-2001 research project of Carnegie Mellon University

Carnegie Mellon University

Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania, United States....

, with the goal of providing cost-effective scalable storage

Computer storage

Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is one of the core functions and fundamental components of computers....

 bandwidth

Bandwidth (computing)

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...

.

Overview

NASD reduces the overhead on the file server

Server (computing)

In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...

 (file manager) by allowing storage devices to transfer data directly to client

Client (computing)

A client is an application or system that accesses a service made available by a server. The server is often on another computer system, in which case the client accesses the service by way of a network....

s. Most of the file manager's work is offloaded to the storage disk without integrating the file system policy into the disk. Most client operations like Read/Write go directly to the disks; less frequent operations like authentication go to the file manager. Disks transfer variable-length objects instead of fixed-size blocks to clients. The File Manager provides a time-limited cachable capability for clients to access the storage objects. A file access from the client to the disks has the following sequence:

1. The client authenticates itself with the file manager and requests for the file access.
2. If the client can be granted access to the file requested, the client receives the network
   Computer network
   A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
   
   location of NASD disks and their capability.
3. If the client is accessing the disk for the first time, it receives a time-limited key for the establishment of secure communication to the disk.
4. The file manager informs the corresponding disk using an independent channel.
5. From now on, the client directly accesses the NASD disks by giving the capability it received and further data transfers go through the network, bypassing the file manager.

External links

• NASD: Network Attached Secure Disks
• Filesystems for Network-Attached Secure Disks Garth Gibson, David F. Nagle*, Khali Amiri*, Fay W. Chang, Howard Gobioff, Erik Riedel*, David Rochberg, and Jim Zelenka, 1997
• File server scaling with network-attached secure disks Joint International Conference on Measurement and Modeling of Computer Systems, archived in Proceedings of the 1997 ACM SIGMETRICS international conference on Measurement and modeling of computer systems, Seattle, Washington, United States, Pages: 272 - 284, 1997, ISBN 0-89791-909-2