1. Introduction

Data transfer and archive are a major step in the processing of astronomical data. Because of high cost in the mass storage hardware and the speed limitation in network communication, an half-decade ago relatively little effort was expended on the archiving of astronomical data with emphasis towards making the raw data permanently on-line and immediately accessible. Due to the recent development in technology the cost of designing and building an on-line archive system has dropped significantly. It becomes possible and can be afforded by a project like the SMA to develop and maintain an on-line archive system. A solid design provides easy and quick access to users and also provides high efficiency and good performance in data management.

The storage and archive techniques used in the modern computer systems are composed of several different hierarchical levels. Four levels are needed to make an archive successful, which can be divided into the two major categories, i. e. hardware and software.

For the hardware,

$\bullet$ 1. the storage medium (such as juke box, disk array, and CD-ROM, tape reel ...);

$\bullet$ 2. the reading or backing up devices (disk drive, tape drive ...).

For the software,

$\bullet$ 3. the data structure on the medium (file system or standard format);

$\bullet$ 4. control and management procedures.

A general discussion on these levels can be found in Pasian and Pirenne (1995).

In this memo, we present the state of the art design for the SMA Astronomical Data Archive System by giving the details of each level. The rest of the memo is organized as follows: In Section 2, we describe the software design and development for the SMA on-line archive system. In Section 3, we will review the prospects of the hardwares that are necessary to implement the entire system. Section 4 gives a few remarks on this system. Section 5 is a summary.