The IBM System 360/370
In 1967, the Trading Banks in New Zealand, formed Databank Systems, providing one of the world's first interbank clearance systems. It was set up and run on no less than 9 IBM System 360's. The Auckland and Wellington centres were put into existing office-buildings, while another four purpose built I.T. Centre buildings were constructed at Hamilton, Palmerston North, Christchurch and Dunedin. There were 2 Model 30's, 6 Model 40's, and a solitary Model 65.
Meanwhile, others with the need of computerisation, like Shell, BP, Dairy Board, NAC, Air New Zealand, etc, etc ordered in mostly Model 30's and the odd 40, so the country was soon awash with them. In those times, machine ownership was not generally offered, as IBM preferred to lease on an hourly basis. (This was only to the client's advantage when the IBM Customer Engineer left his key in the console switched over to the CE meter, rather than the client's charge-out meter, although this was very rare !)
Our personal experiences were firstly on Databank's 360/40 in Christchurch, then at Shell Oil's H/O on the Terrace in Wellington running a 360/30. This one was interesting, as it had the optional 1401 emulator, enabling it to run programs written by Shell at the Hague, for the IBM 2nd generation 1401 machines that preceded the System 360. Once a day, we shut this system's DOS operating system down, and rebooted it under OS, in order to run the planning programs for the Marsden Point Oil Refinery. We helped push this out the door, the day it was replaced with a 370/135 at Shell, only to wind up doing the same thing again another year later at the Dulux site in Lower Hutt. (It looks like at least one of IBM's leased machines, got a second lease of life, before it went to the tip.)
A succession of machines followed, with 370/125's at P&O Shipping and NZIG (although P&O's soon demanded a 370/138 to cope with the workload). National Bank was the first of the Trading Bank partners in Databank, to form its own large I.T. Centre, and this was equipped with IBM 4381's, first in Commercial Union's old centre, then over the course of a weekend, the whole lot was moved over the road to the then brand-new Brittanic House (now occupied by Telecom and Gen-I). The last bit of experience with IBM iron, was at the NZPO H/Q, where we ran an IBM 4331, a Facom M380 (IBM 370 clone) and an earlier ICL System-4/72 (virtually an IBM 360 clone). Maybe, one of these machines, is still around somewhere.
Server farms started popping up in the 1990's, so before long, the mainframe had gone from all but the very largest data centres. Their size, plus the cost of housing and running them was prohibitive compared to the new servers, so an era finished.