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Comment by gosub100 | Hacker News Reader

I seriously doubt there's a POWER mainframe in the back of Costco to handle the 3 UPC barcode scans per second. It's possible that every Costco store funnels its orders to a single mainframe somewhere.

I think a more realistic case is the visa and MasterCard credit card networks that have almost 0% downtime.

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No such thing as a POWER mainframe. IBM's POWER lines (i and p) are different from their mainframe line (z).

Not a POWER Mainframe, no. But AS/400's come in many sizes. The smallest ones are roughly the size of a standard workstation

Back in 1994, they were small enough like a big PC tower, I used to seat on one occasionally, that was out of order.

One of my Summer intern jobs was to run backups every few days on a AS/400 system.

That "seat" was the old one that was yet to be collected.

> Back in 1994, they were small enough like a big PC tower,

Back then their model lineup ranged from the small size like you mention to approx 3 or 4 refrigerator size at the high end.

When I did some system work out at Costco in the 90's they had 4 of the largest models connected together in one system image (sysplex I think).

Indeed, never saw other sizes in real, only on magazine ads.

Just for completionism, two decades back the absolute smallest zSeries was a "rolling box", low and squat, that just barely fit into an office building elevator. Think of a short rack tipped on its side with wheels, but all a single computer. IBM loaned us one to port our Linux software to it. Normal zSeries are like a custom rack to multiple racks, except again all a single computer.

The smallest iSeries I've seen was essentially an "oversize tower PC" form factor.

Mainframes are not POWER, they are z/Architecture.

For AS/400 (IBM i), they're POWER, but come in pretty small models like IBM Power S1012, it's available as "deskside", i.e. a big tower.

I think it's more likely they have a rack of IBM iSeries servers in the back someplace, or maybe in a colo data center.

I can provide some insight into this. Most stores will have a server which handles the barcodes, pricing, etc, locally. Then all transactions are usually sent in a batch everyday from the store server to a central server/servers somewhere for processing, usually around that time reports are also generated and stats made available for BI analysis.

Payments processed by the payment terminals handle the authorization of the payments separately from any store servers, usually through a service such as Connected Payments.

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