The other day I was trying to decode the “lot numbers” printed on certain Seagate drives. In the meantime, I realized that those lot numbers have been in use for quite some time. They were in use around 2000, like on this Cheetah 73 made in 2001:
They can be found on Seagate’s drives going back into the early 1990s, but always only on some of them—typically on higher-end enterprise drives, almost exclusively using SCSI/FC/SAS interfaces. One older example is this 1994 DEC-branded RZ25-E drive, which is definitely a Seagate-made drive and almost certainly a model ST1480N:
As it turns out, those lot numbers aren’t a Seagate invention. It’s something that Seagate adopted when it acquired (1989) the drive maker Imprimis, a subsidiary of CDC (Control Data Corporation).
While Seagate built a lot of drives in the 1980s, their drives weren’t particularly technologically advanced. That made them cheap and reliable, but not especially fast. CDC/Imprimis made a lot of minicomputer drives (including 8″ and larger monsters), and those drives were good performers.
In the PC arena, CDC/Imprimis Wren and Swift drives were well known. The above Digital RZ25-E alias Seagate ST1480N is in fact an improvement of the CDC Swift, CDC’s first 3.5″ drive (of course half-height, therefore with a Seagate model number starting with 1 rather than 3) which appeared circa 1988.
CDC was—like Seagate—an early adopter of SCSI, and also the first maker of dedicated IDE drives as a Compaq OEM. Seagate kept a lot of the Imprimis drives in production for several years. At least one product line, Elite (large capacity full-height 5.25″ drives), survived until about 1999.
Here’s a label on an Imprimis-branded drive from 1989 or 1990:
Why the uncertainty? It is clear that for recent Seagate drives, the date code refers to Seagate’s financial year, which starts in July of the previous calendar year. For example, Seagate’s 1995 financial year started on July 1st, 1994. But it’s unclear if that was already the case with the Imprimis drives. It could well have been the case with the above drive, given that Seagate completed the Imprimis acquisition in mid-1989. There is in fact clear evidence that Seagate sold drives with an Imprimis label. And they had those same lot numbers.
Whatever the exact history, the lot number designation with a date code came to Seagate from Imprimis, possibly specifically from the Oklahoma City branch of CDC/Imprimis. It was used for some, typically high-end, Imprimis and Seagate drives at least since 1989 or 1990.
Seagate appears to have stopped using the lot number labeling after their circa 2011 rebrand, though it remained in use for existing models until those went out of production. Seagate’s current (as of 2020) enterprise drives usually have a straightforward DOM (Date Of Manufacture) label.