Network-Attached Secure Disks
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Network-Attached Secure Disks (NASD), a research project of Carnegie Mellon University provides cost-effective scalable storage bandwidth. NASD reduces the overhead on file server (file manager) by allowing storage devices to transfer data directly to clients. Most of the file manager's work is off-loaded to the storage disk without integrating the file system policy into the disk. Most of the client operations like Read/Write directly go to the disks directly and less frequent operations like authentication go to the file manager. Disks transfer variable length objects instead of fixed size blocks to clients. File Manager provides a time-limited cachable capability to clients to access the storage objects. A file access from the client to the disks have the following sequence:
- 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 Network location of NASD disks and the capability.
- If the client is accessing the disk for the first time, it receives a time-limited key for 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.
