【NEC】 ACOS-4/i-PX

ACOS-4/i-PX (which stood for “internet − parallel extended”) was an operating system designed for NEC’s mid-range and large mainframes. NEC announced and began shipping the operating system in November 2000.

ACOS-4/i-PX was developed for enterprises to expand into full-fledged Internet businesses by harnessing the Internet to more effectively use corporate information assets accumulated on mainframes. ACOS-4/i-PX provided scalable HA infrastructure, which made use of the latest Parallel ACOS system hardware technology and ensured continued future expandability, storage infrastructure, which offered new solutions to data usage, and Internet infrastructure, which seamless connected the system with the Internet. The operating system was installed on the i-PX7600 Parallel ACOS system, announced in November 2000, and the i-PX7800, announced in June 2001.

The main features of the operating system and its new architecture are detailed below.

1. Scalable high-availability (HA) infrastructure

ACOS-4/i-PX strengthened the scalable HA infrastructure and maximized the functionality and performance of Parallel ACOS systems. More specifically, it gave better scalability to make it possible to expand a system gradually, both in data storage and processing capability. It also increased availability by ensuring that the entire system would not go down or that the performance would not deteriorate in the event of a failure.

(1) 64-bit architecture support

One aspect of improved scalability was the operating system’s support for 64-bit addressing, which made it possible to have large-capacity main memory storage and massive virtual memory storage.
One key benefit was the ability to use much larger operating system buffers in main memory, thereby increasing buffer hit ratios and improving overall performance.
ACOS-4/i-PX provided a function that generated a virtual disk region (memory disk) in main memory that was accessible in the same way as a physical disk unit. The memory disk increased application throughputs when used for data sorting and other operations that needed high-speed disk access.
Thirdly, ACOS-4/i-PX increased the user space per job from 512 MB to 1 GB, giving enough memory to run large user programs.

(2) Enhanced cluster system infrastructure

ACOS-4/i-PX provided a service-distribution cluster system configuration along with the existing load-distribution cluster system configuration. The advantage of a service-distribution cluster is that, by assigning an active system to each service, it was possible to build systems with excellent scalability and availability while remaining easy to migrate from existing (single host) systems. Switchovers in the event of a service fault were made faster by launching a standby service beforehand on another host for each active service.

2. Storage infrastructure

ACOS-4/i-PX provided a storage infrastructure that used the iStorage series of SAN-compatible storage products.

(1) Storage integration

By providing an integrated storage environment for Parallel ACOS machines and open servers, ACOS-4/i-PX cut the management costs of stored data scattered among multiple servers, and thus reduced TCO.

(2) Integrated storage management

ACOS-4/i-PX provided iStorageManager, a storage management software program that integrated the management of storage. iStorageManager centralized the management of multiple iStorage sites and had functions for managing the organization of storage, monitoring for faults, and monitoring performance.

(3) Data replication

ACOS-4/i-PX had a data replication function that immediately made duplicate work disks within the same storage system or between different storage systems. The data replication function was used for the following applications:

• Using the duplicate disk for backups made it possible to run online services and backups in parallel, which made backups more efficient and reduced the online service’s down time.
• Using the duplicate disk for developing services made it possible to easily evaluate the service using live data. This stabilized the quality of service applications in a shorter amount of time.

3. Internet infrastructure

ACOS-4/i-PX provided iPackage, the functions and Internet infrastructure to enhance services to work with the latest Internet technologies while continuing to use previous services without needing any modifications.

iPackage was based on three main concepts (Figure 3), given below. All of them enhanced service levels by placing an open server as the front end to a Parallel ACOS machine and making use of the latest Internet technology.

(1) Convert existing services to work with the Web

iPackage included connector technologies to use core services on Parallel ACOS machines from the Web. It had a packaging product that converted core service input and output messages into HTML, XML, and CORBA and an interface product that connected to applications on open servers.
Core service input and output messages could be processed transparently on open servers by means of OLF/TP and previous ETOS-based core services could be enhanced by adding application processes to their input and output messages.

(2) Database access

iPackage came with functions giving open servers direct access to data used by core services on Parallel ACOS machines. One product gave open servers direct access to RIQS databases via an ODBC/JDBC interface or an Oracle interface. Another product gave open servers direct access to VSAS files and ADBS databases through SQL. These products made it possible to use a Parallel ACOS machine as a database server and made it easier for open servers to use core data.

(3) Database transfer

iPackage came with functions to transfer RIQS databases or VSAS files used by core services on a Parallel ACOS machine for independent use on an open server. Applications of this functionality include the transfer of a core database to a number of departmental servers at different sites to carry out strategic analysis or data input services without impacting the core service. Databases could be transferred in their entirety or in increments of updated data records only. Sending just the updated data made it possible to reflect new data virtually in real time for a more powerful information system. iPackage also provided a function for transferring data from an open server to a RIQS database on a Parallel ACOS machine to address needs for bidirectional use of core data.