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Evolution of storage facilities in AIX Version 3 for RISC System/6000 processors

 Award plaque by A. Chang,
M. F. Mergen,
R. K. Rader,
J. A. Roberts,
and S. L. Porter

The AIX® Version 3 storage facilities include features not found in other implementations of the UNIX® operating system. Maximum virtual memory is more than 1000 terabytes and is used pervasively to access all files and the meta-data of the file systems. Each separate file system (subtree) of the file name hierarchy occupies a logical disk volume, composed of space from possibly several disks. Database memory (a variant of virtual memory) and other database techniques are used to manage file system meta-data. These features provide the capacity to address large applications and many users, simplified program access to file data, efficient file buffering in memory, flexible management of disk space, and reliable file systems with short restart times.

Originally published:

IBM Journal of Research and Development, Volume 34, Issue 1, pp. 105-110 (1990).

Significance:

The AIX® Version 3 storage facilities marked a notable point in the evolution of storage systems within the framework of the UNIX® operating system and included features not found in other implementations of UNIX. The storage system discussed in this paper for the IBM RISC System/6000® provided support for large software applications and large numbers of users, direct access to file data using ordinary program statements, more efficient file buffering than that provided by fixed-size buffer pools, more flexible units of disk-space management than provided by fixed-size disks, and a file subsystem that recovered from crashes and had a shorter restart time than in previous related operating systems. The important concepts used in this storage facility evolution included very large virtual memory, integration of the file subsystem with logical volumes and virtual memory, and the innovation of database memory.

The architecture extensions of the IBM RISC System/6000 processor and the AIX Version 3 implementation provided a total virtual space of more than 1,000 terabytes. Logical volumes and file buffering in virtual memory allowed file systems to grow to very large configurations with little space management and tuning effort. File-space mirroring and database memory improved file system availability, reliability, and recovery time. Although some of the ideas described in this paper were not new in isolation, their combination in an industry-compatible workstation product was unique.

For a more general paper on the evolution of storage systems in order to obtain highly reliable, high-performance, and easily managed systems, see “The evolution of storage systems” by R. J. T. Morris and B. J. Truskowski. This paper includes such topics as RAID (redundant array of independent disks), NAS (network-attached storage), and SAN (storage area network) technologies. For an overview of early developments of storage management techniques, particularly those used in OS/360, see “Functional structure of IBM virtual storage operating systems, Part I: Influences of dynamic address translation on operating system technology” by M. A. Auslander and J. F. Jaffe.

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