Editing Network-attached storage (section)

=== Network-attached secure disks===
'''Network-attached secure disks''' ('''NASD''') is 1997&ndash;2001 research project of [[Carnegie Mellon University]], with the goal of providing cost-effective scalable [[Computer data storage|storage]] [[Bandwidth (computing)|bandwidth]].<ref>{{cite web|url=http://www.pdl.cmu.edu/NASD/|title=NASD: Network attached secure disks}}</ref> NASD reduces the overhead on the file [[Server (computing)|server]] (file manager) by allowing storage devices to transfer data directly to [[Client (computing)|client]]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:

# The client authenticates itself with the file manager and requests for the file access.
# If the client can be granted access to the file requested, the client receives the [[Computer network|network]] location of NASD disks and their capability.
# 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.
# The file manager informs the corresponding disk using an independent channel.
# 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.