Mainframe support

Adam Turoff ziggy at
Mon Mar 29 12:30:40 PST 2004

On Mon, Mar 29, 2004 at 10:28:00AM -0800, Johnson David wrote:
> On Sunday 28 March 2004 08:41 pm, Charon wrote:
> > IBM is currently pushing Linux on its big iron offerings. What
> > similar capacity options are available for FreeBSD based
> > installations? Has IBM actually ported Linux or are they running a
> > smoke and mirrors setup with Linux running in a vmware like
> > environment?
> IBM ported Linux itself to their mainframes. It wasn't a community 
> project in any sense of the word. 

Actually, I think the initial work was done by a few hackers in Germany.
I don't remember if IBM took this work and fleshed it out, or if they
had a similar project already, and were waiting for customer demand to
polish it up and release it.

> We could do this, but I don't think 
> anyone here can afford an IBM mainframe. Heck, most of us couldn't 
> afford the real estate to house one :-)

That's not strictly true anymore.

I came across a reference to an open source project that provides 
VM hardware emulation.  So you could run Linux under VM, or MVS, or any
other VM hosted operating system on a stock x86 box.  It was supposed to
be a pretty faithful emulation, and was able to scale to a few
concurrent OS instances on a reasonably powered vanilla box.

Sorry, I don't have a reference for you.  I don't remember where I saw
it, but it was within the last 2 weeks or so.

> There are practical and philosophical problems with Linux on their 
> mainframes. First, this is a niche market. The only customers are going 
> to be banks and other transaction-heavy Fortune 500 companies. It's a 
> "brownie point" for Linux, but nothing to be ashamed of if you don't 
> have it. Second, Unix and mainframes have completely different skill 
> sets. Going with this solution means you need both mainframe and Linux 
> administrators.

Looking historically, yes.  

However, Unix is moving in this direction anyway.  With UML, jail, and
the like (including partitioning and virtualization of high end Solaris
machines), we're moving to a situation where an admin will set up one
physical machine with a dozen or so virtual environments running
concurrently on that hardware.  I think Linux is one step ahead at the
moment -- UML or one of the other virutalized Linux/x86 environments can
run multiple kernels concurrently in userland, while jail provides the
ability of running the same kernel in multiple sandboxes.  

So while IBM's VM per se may only be interesting to the Fortune 500,
virtualization is gaining traction, especially at the low end of the
spectrum.  ISPs for example have been offering accounts on virtual
machines for a few years now.  I wouldn't be surprised to see shops that
used to buy vanilla boxes in groups of 4 to soon start buying boxes one
one by one, adding a few GB of RAM and at least 1 TB of disk, and
partitioning them on demand.

> Philosophically, from the Free Software side of things, it's kind of 
> strange. You have a Free Software kernel running in a VM in a 
> proprietary operating system on proprietary hardware with only one 
> vendor available for support. Overall, there's few advantages for the 
> customer, but large advantages to IBM.

That's one way to look at it.  But how is this different from free
software running on proprietary hardware (e.g. a PowerBook or an iMac)?

> It would be nice if FreeBSD could run in the Z-Series, if only for the 
> brownie points we would earn. But it would be little more than an 
> experiment. You're not going to run a webserver on an IBM mainframe, or 
> make it your development workstation or desktop. The only applications 
> that would make sense could still be done cheaper on a cluster.

Depends on the economics of the situation.  There are real costs for a
shop like Google to keep 10,000 machines up and running 24/7.  For some
customers, and for some applications, it is more cost effective to run
on a Z-Series.  Yes, they tend to be banks and Fortune 500.  The
economic conditions are not constant, nor are they universal.


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