25th Anniversary of the Personal Computer" 4211

from long ago and far away ... Harrier is code name for what became 9333 (which later turned into SSA). Note that the last item mentions "checksum disks" ... this is commoningly referred to now as raid.

To: wheeler

---------------------------------------------------------------------- Hursley trip issues-facts-enhancements:

- DASD Format: (fact) - Track format, ECC, ERPs functionally identical to SCSI Redwing. Comment: Potentially,by changing SCSI Redwing controller card to serial card, the drive can be attached under Harrier.

- Serial link: (fact) - Full duplex link - Packet Multiplexed - 9 MB-S speed - Packet format like X.25

... snip ... and the last item:

- Checksum disks - This is for availability. - Will have WRITE performance impact Comment: This feature is used by A-S 400 or S-38. It has questionable value in Rios. If no comment, this feature will be rejected.

... snip ...

old post on raid

the above includes following ref from a URL

1978

First patent for RAID (Redundant Arrays of Independent Disks) technology. IBM subsequently co-sponsored the research by the University of California at Berkeley that led to the initial definition of RAID levels in 1987.

The first two-speed tape unit, raising streaming speeds to 160 kb-second.

Hierarchical Storage Manager (HSM), which provided customers system-delivered migration of inactive data from disk to less expensive tape.

... snip ...

however, that URL no longer exists ...

so to wiki

... from above:

Norman Ken Ouchi at IBM was awarded U.S. Patent 4,092,732 breastled "System for recovering data stored in failed memory unit" in 1978 and the claims for this patent describe what would later be termed RAID 5 with full stripe writes. This 1978 patent also mentions that disk mirroring or duplexing (what would later be termed RAID 1) and protection with dedicated parity (that would later be termed RAID 4) were prior art at that time.

RAID technology was first defined by a group of computer scientists at the University of California, Berkeley in 1987. The scientists studied the possibility of using two or more disks to appear as a single device to the host system.

In 1988, RAID levels 1 through 5 were formally defined by David A. Patterson, Garth A. Gibson and Randy H. Katz in the paper, "A Case for Redundant Arrays of Inexpensive Disks (RAID)". This was published in the SIGMOD Conference 1988: pp 109-116. The term "RAID" was first introduced in this paper; it spawned the entire disk array industry.

... snip ...