NAStore 3.0

Overview

NAStore is a modification to UNIX which allows files to transparently migrate between disk and cheaper, removable storage (tape). Its main software components are:

The 3.0 design moves from a single large UNIX host configuration to a multi-host distributed system connected by a high-speed switched internal network. Each of the logical components can be hosted by one or more physical hosts attached to the internal LAN. For example, in our first production target diagram, we plan to use two SGI origin 2000's and two DEC Alphaserver 8200's to provide users access to their data via traditional interfaces like NFS, RCP, FTP or login. The system is highly scalable, limited mostly by the maximum "feasible" size of the internal network fabric and by contention for shared resources within the system. But, unlike many other such systems, the logical components may be run on a single host where a smaller [initial] system is needed, although the multi-host configuration allows for greater redundancy, and consequently nearly uninterrupted access to data. One important thing to note is that depending on how you design your internal network, one can scale performance and/or capacity allowing one to build a system that can perform traditional data archival duties as well as provide direct attatchment to the shared filesystem for applications such as Unsteady Flow Visualization where Terabytes of data are analysed at very high data rates. ( for a discussion of this topic, warts and all, go here for a discussion of how this is currently being done)

Another major innovation with the 3.0 design is the use of disk caching of migrated files to allow better bandwidth to tape and faster restore times. Migrating a Virtual Volume between disk and secondary storage allows high capacity, high speed tape devices, e.g. STK D3, to stream data to tape much more rapidly than smaller single file transfers. Also, by retrieving and caching an entire Virtual Volume rather than a single file, expensive tape seek and mount activities are reduced when using very high capacity tapes. (since seek times often increase and number of drives may decrease)


Available Documentaion

Reference Documentation Hardware and Software
Evaluation Data
Older Papers and
Documentation

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