Getting pretty off-topic: database systems

Vincent Trouilliez vincent.trouilliez at
Mon May 23 08:26:42 UTC 2005

> IBM have four ranges of servers:
> The xSeries, which are PC based (Xeon, Opteron and Itanium), running PC
> operating systems.
> The pSeries, the successors to the RS/6000 line, which run AIX (IBM's
> Unix). They're the equivalent of what Bull sells, and run on Power /
> PowerPC hardware.
> The iSeries, the successors to the AS/400 line of midrange computers.
> They run OS/400 (aka i5/OS) with a built-in database. It's a weird and
> highly virtual operating system: see
> for more details.
> And the zSeries, the successors to the S/390 and S/360 mainframes. They
> run z/OS and z/VM. The S360s were the 1960s mainframes that built IBM's
> computing reputation. Modern mainframes are very different beasts to
> their forebears and to smaller computers: they tend to be
> ultra-reliable, able to spot hardware failures, work around, and swap
> out dodgy hardware without affecting user programs. They also have the
> ability (now coming to other computers) to run lots of "instances" of
> operating systems in parallel.
> IBM offer Linux on all of them. But running Linux on a mainframe doesn't
> just make it a very big and expensive PC. You still get all the
> reliability, and all the ability to run thousands of instances of
> operating systems independently. You can "consolidate" thousands of PC
> servers onto one mainframe, each server's tasks being adopted by one
> Linux instance. So it looks to software and to end users like it's
> lots of computers. But it's still only one computer: it's a lot cheaper
> to administer and look after than hundreds of individual servers.
> And that means that for a lot of companies, an IBM mainframe is the
> cheapest way of running a lot of Linux instances. They want to run Linux
> because Linux has the applications they want to run and z/OS doesn't
> (although you can run that in another partition).
> It's turned IBM's mainframe division around, and has been making IBM a
> lot of money.
> James.

Ah, thanks for the info James, it was an enjoyable and informative read,
I am less in the dark now, and spent some more time browsing the IBM web
site again. Seems like the machines I was working on at Bull, with nodes
under the name of "PL820", were very very very similar to the top of the
range of what IBM lists on their site as "mid-range eServer p5 series"

Other people were working on bigger machines, by the looks/width of the
cabinet, it was either the high-range p5 series (595) or zSeries
mainframe. Never looked at them that closely as they were not assembled
in my part of the building and can't remember what OS they were running,
so can't be sure... 

Anyway, thanks for all the info...


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