【Hitachi】 A-6531，A-6533 Disk Array Units

The A-6531 was a compact disk array subsystem announced by Hitachi in April 1995 that was developed to meet the demand for smaller, faster, more reliable computer systems.
The A-6531 was a magnetic disk unit optimized as an external memory device for next-generation open systems, such as data server workstations or PC-LAN servers, and, using RAID technology, it offered high reliability, high availability, and high performance in one unit.

Features of the A-6531:

• （1）It used a RAID-5 array, which allowed data to be recovered from another disk and processing to continue should a disk fail.
• （2）The industry-standard SCSI-2 interface gave it connectivity with many types of systems.
• （3）Its high transaction performance was derived from non-volatile cache memory between 4 and 128 MB.
• （4）Four model types were offered to flexibly meet the end-user’s application; the subsystem capacity and cache memory size could also be selected to fit a wide range of systems.

The A-6533 was a compact disk array subsystem announced by Hitachi in March 1997. To meet the need for high performance, large capacity storage in the rapidly growing open market, the A-6533 almost doubled the data transfer performance of the A-6531 by speeding up the previous model’s processor and internal bus.

The A-6533 had the following enhancements over the A-6531:

（1）Faster processor and internal bus

（2）Larger non-volatile cache memory (expandable up to 1 GB)

（3）Used fast, large-capacity disk drives

（4）Came with an Ultra SCSI interface