
IBM launches Linux-only mainframe system - jeo1234
http://www.reuters.com/article/2015/08/17/us-ibm-linuxone-idUSKCN0QM09P20150817
======
aus_
By trade, I am a mainframe systems programmer at a large financial
institution. My group is responsible for mainframe operating systems: z/OS (it
may also be referred to as MVS), z/VM (the mainframe hypervisor), and z/Linux
(Linux on a mainframe) and many of the software components that go along with
these.

I'm really excited about this announcement. I think IBM finally realized they
need to be more open if they want to grow the Linux on z community. I just
hope they are not too late to the game.

There's a lot of mystery and misconception behind mainframes, so I am happy to
answer any questions about mainframes that I can.

~~~
mozumder
So, why use Linux instead of z/OS? Is it cheaper? Offer more tools?

~~~
aus_
It's hard to answer "z/OS vs Linux on z" generically, because there's use
cases for both. But perhaps the most generic answer I can give you in favor of
Linux is: familiarity.

z/OS has a long history. It's predecessor, OS/390, dates back to the 1990s.
Before OS/390, there was OS/360 which dates back to the 60s. Back then, IBM
was first to market on business computer processing. (That was the only
computer processing.) Major industries, like financial, insurance, and
airlines, poured their infrastructure into mainframes, because it was the only
name in the game. IBM prides itself in assuring its customers that the COBOL
code that ran your business back in the 80s will still run today on z/OS 2.1
(the current version of z/OS). Chances are, when you swipe your credit card,
that transaction touches a mainframe and probably some code that was written
in the 1980s. Or earlier. I know, because I've seen the timestamps.

This compatibility is really evident when you use z/OS. The green screen is
perhaps the most obvious example. When you see a systems programmer (that's
mainframe-talk for sysadmin) debugging a system, you'll see them page through
a really archaic, unsexy TN3270 interface. Why? The same reason Unix (and
thereby Linux) uses teletype. Because that's what the operating system was
built on.

Sure. z/OS has Unix System Services. In fact, it's even POSIX compliant. But
can you `apt-get install ruby`?. No. There's no Ruby for z/OS (unless you
count JRuby). There's no package manager for USS. It's just plain, vanilla
Unix. There's no new open source contributions. There's no Bash that comes
with the operating system. You get a 10 year old version of Shell. There's all
kinds of shenanigans with SCP/SFP and ASCII/EBCDIC. IBM has to maintain the
tools. (Actually, it's been turned over to Rocket Software.) It feels very
"round peg, square hole".

So z/OS has an image problem. IBM made a huge mistake back in the mid-80s.
When commodity x86 PCs became available, universities realized they could
teach their computer science programs on cheaper hardware instead of expensive
mainframes. Compute Science is platform agnostic, right? What IBM didn't do is
recognize this as a problem. They didn't give out free mainframes to
universities, so schools quit teaching with them. How many people do you know
under 30 that had a mainframe-based curriculum? And for the self-taught, how
are you suppose to learn the basics of a platform if costs millions of
dollars? Anybody can install Linux on their $100 laptop in a few hours. But
mainframes?

Fast-forward a couple of decades and now you have a talent pool that's
extremely saturated with x86 people. And the mainframe people? Well, they are
all retiring and there aren't many replacements. Second-generation mainframers
are far and few. (I'm one of them.)

So let's say you have a new workload. It's undeveloped. What platform should
you choose? There's probably not many technical reasons why you could not
accomplish what you want to do in z/OS. But how many people do you know that
consider themselves proficient with debugging z/OS? Outside of "dead
languages", your options are pretty much limited to Java. (There's a few
exceptions to this, but Java is the biggest modern language player.) But
that's not to say there isn't any new development happening in the z/OS space.
There's plenty of new workloads coming to WebSphere on z because porting a
WebSphere application could be pretty easy. There's also performance benefits
when you are on the same system where all your financial records are stored.
z/OS is definitely an option, but it varies by use case.

With Linux on z, you get real Linux. And the majority know Linux. The majority
can debug Linux. And you get the same benefits of being on rock-solid
mainframe hardware and you get memory-speed I/O against mainframe data and
services through a special networking interface called Hipersockets.
Mainframes are also pretty good a virtualization, because they invented it.
(z/VM has it's roots dating back to the 70s.)

~~~
nickpsecurity
That was definitely where they screwed up: universities. They have recent
program pushing mainframes to universities more. However, they would've been
better off (a) giving them to Universities at physical cost, (b) donating time
to their students from a pool IBM themselves use, or (c) supporting the
Hercules emulator for use in educational institutions that acquire licenses.
This would've gotten more exposure. Each are still good moves today.

Not sure what they're actually doing but closing it off too much holds them
back. It can still be proprietary. However, people need to be able to hack on
it or a VM of it for best results. Preferably, a way for people to learn it in
pieces so they don't have to know all mainframe stuff at once. Think the pre-
configured, appliance VM's for various services. Have those for z/OS admins,
CICS users, etc.

------
cm-t
Note: Canonical seems to be a partner to bring Ubuntu on it

See [http://techcrunch.com/2015/08/16/ibm-teams-with-canonical-
on...](http://techcrunch.com/2015/08/16/ibm-teams-with-canonical-on-linux-
mainframe/)

~~~
cm-t
Confirmed here: [https://insights.ubuntu.com/2015/08/17/ibm-and-canonical-
pla...](https://insights.ubuntu.com/2015/08/17/ibm-and-canonical-plan-ubuntu-
support-on-ibm-z-systems-mainframe/)

------
gauravphoenix
"IBM said LinuxONE Emperor can scale up to 8,000 virtual machines or thousands
of containers, which would be the most for any single Linux system."

I wish article (or IBM) provided some specs. Thousands of containers is just
too broad of a statement- what are these containers doing? Running just a bash
script _hello world_ program or minting bitcoins?

~~~
otis_inf
In an article which states "..IBM's z13 mainframe computer, which had been
designed for high-volume mobile transactions.", all bets are off with respect
to reality. I mean, what does 'designed for high-volume mobile transactions'
even mean in the context of having Linux running on the hardware?

~~~
ams6110
Not sure if this is still correct for the z13 but in general: "System z
servers offload such functions as I/O processing, cryptography, memory
control, and various service functions (such as hardware configuration
management and error logging) to dedicated processors."

(from Wikipedia)

~~~
bridanp
It's called a zIIP engine
([http://www-03.ibm.com/systems/z/hardware/features/ziip/](http://www-03.ibm.com/systems/z/hardware/features/ziip/))
and it utilizes the IFL also
([http://www-03.ibm.com/systems/z/os/linux/solutions/ifl.html](http://www-03.ibm.com/systems/z/os/linux/solutions/ifl.html)).
We use the zIIP on our z13 basically to offload any work that takes a ton of
I/O (DB2 data serves, dataset scans for performance monitoring, RMF and CICS
reporting). It ends up saving a lot of money monthly because we are charged by
maximum number of MSU's during any four-hour window of the month. The zIIP
reduces the number of MSU's needed at any given time. In our case, 5-10.

Back in 2005, I installed SuSe on an s/390 box. If you could throw a lot of
memory at it or MIPs, then it would run pretty well, and could be used as a
file or email server. But anything that crunched data was horribly slow. Can't
say that it's any better now, but if it's utilizing the zIIP, I'm sure it's
miles above where it was 10 years ago.

Still, pretty high cost of ownership on the mainframe to get this. I can't
imagine many people buying a million dollar mainframe just to run Linux. Seems
like those who have a mainframe already would have been like us: let's
partition out a Linux instance and try it out.

~~~
aus_
To clarify, zIIP processing is only relevant under z/OS. Linux processing runs
under IFLs. But that's not to say you can't get some offloading in Linux. By
design, mainframes can hardware accelerate some processing. The crytpocards
[0] are an example of this.

But you are right. A lot of shops go through a lot of effort to maintain their
zIIP window in their z/OS processing. And a big selling point for many
mainframe software vendors is that their product's processing is "zIIP-
enabled".

[0]:
[https://share.confex.com/share/120/webprogram/Handout/Sessio...](https://share.confex.com/share/120/webprogram/Handout/Session12687/Share12687_IntroToCryptoOnSystemz_20130203.pdf)
(slide 30)

~~~
bridanp
Yes, you are right there, and thank you for clarifying that. I should have
been more clear that the zIIP is useful to Linux through accessing data via
z/VM. You can't offload all of the I/O, but you can offload some of it if
accessing the mainframe for data. Or so I remember at this point. It's been a
few years since leaving my mainframe systems programmer position.

------
rodgerd
From my experience with zLinux environments I would be inclined to scrutinise
any density claims very, very carefully.

Interesting they're working with Canonical on this - the Z has historically
been a SuSE stronghold, with a lot of the development of Linux-on-Z happening
in Germany, and Red Hat trailing behind. I'd be wary it will be another
increasingly typical adware effort from them.

(I follow the main zLinux mailing lists for my day job, and I see a lot of
folks from SuSE, some folks from Red Hat, a bunch of people from IBM, and
basically no-one from the Ubuntu/Canonical world. Usual disclaimers apply.)

~~~
jacques_chester
> _Interesting they 're working with Canonical on this_

Ubuntu's distributions are the reference root FS for Cloud Foundry, to which
IBM is the second largest contributor of treasure and engineering effort.

Disclaimer: I work for Pivotal, who are the first.

~~~
_delirium
Ubuntu also inherits quite a bit of 's390x' platform compatibility work from
Debian. For a user coming from a non-mainframe Linux background who wants the
normal packages to "just work", it might be further along than other Linux
distros (but: I have not quantified this). Debian-on-Z doesn't have as much
testing as x86, of course, but since it's one of the five officially supported
Debian architectures (x86, ARM, PPC, MIPS, S390x), it gets constant autobuilds
of the whole archive, a reasonable amount of debugging effort, and release-
engineering attention.

------
tristor
Frankly, my experience on mainframes is that UNIX is a stronghold there for a
reason. I'd be far more interested in this ecosystem opening up by having
strong mainframe vendor support for running Illumos and/or FreeBSD, and less
concerned with running Linux. Among other things, Zones are more useful than
lxc, and in this type of environment you often need strong kernel support for
specialized high-speed interconnects and real-time operations, which Linux
only has experimental support for but is integrated well in the UNIX world. I
love Linux and what it's done for the world, but UNIX isn't dead for a reason,
there are still many things it is superior at.

~~~
the_why_of_y
This is an odd remark - apparently AIX/ESA, the AIX version for mainframe
hardware was discontinued "in the late 1990s", roughly the same time when IBM
started to invest in Linux.

[http://www.lookupmainframesoftware.com/soft_detail/dispsoft/...](http://www.lookupmainframesoftware.com/soft_detail/dispsoft/1581)

There was also Amdahl UTS, which was sold to a company UTS Global around 2000
that appears defunct now.

[https://en.wikipedia.org/wiki/Amdahl_UTS](https://en.wikipedia.org/wiki/Amdahl_UTS)

So where is this stronghold of AT&T descendant UNIXes on mainframes then?

~~~
tolle
Nowhere, but some people call System I/(A/400)/I-Series a mainframe. It's
midrange, but people call it what they call it.

Anyway, IBM i and AIX run on the same hardware. They used to be called System
I and System P. Now it's just Power Systems.

Maybe thats what he ment.

Or well, come to think of it. There is a UNIX side to z/OS itself.

------
nickpsecurity
It's about time. This is long overdue. The combination of the mainframe
architecture's strengths with Linux's API/ecosystem could be pretty awesome.
Anyone wondering why buy a mainframe should focus on these areas:

1\. Reliability. Some have gone 30 years without downtime. Probably strongest
selling point.

2\. Channel I/O [1]: dedicated I/O processors plus scheduling that lead to
high utilization (80-90+%) and throughput vs commodity servers. Second
strongest point in mainframe's favor. I wish my desktop & servers had this
rather than a knockoff.

3\. Hardware partitioning that's more robust and rated at stronger security
than most virtualization. Certain cutting-edge projects in INFOSEC are doing
similar things at CPU and I/O layers. Mainframe's version, although not as
cool, is decent and field-proven.

4\. Built-in, proven software virtualization.

5\. Hardware acceleration for some things such as databases and crypto.

6\. IBM's ecosystem of apps, third-party providers, and services. This might
matter to existing IBM customers.

So, those are a few advantages I hear from people who use mainframes. The
z/OS-based mainframes have extra benefits in terms of software reliability,
security through obscurity (obfuscation), and seemingly better use of both
security (eg memory key) and functional (eg decimal) aspects of mainframe
processors. The z/VM product has also been doing for decades what modern
virtualization systems only recently do, even self-virtualizing since 70's.

So, there's some things to ponder. Whether it makes since financially vs other
setups is a whole, different discussion. However, mainframes do retain strong,
technical advantages over commodity architectures. They were doing cloud in
one box before it was a thing. Their reliability is still unmatched with only
VMS clusters and NonStop architecture getting close. So, it's a sensible
choice for a business to spend extra $$$ to get high-throughput with no
downtime and strong isolation of logical partitions.

Channel I/O [1]
[https://en.wikipedia.org/wiki/I/O_channel](https://en.wikipedia.org/wiki/I/O_channel)

------
arca_vorago
So for a business with a complex AS400 system still in place, would this be a
replacement for that or an augmentation of that? Their page isn't very clear.

[http://www-03.ibm.com/systems/z/os/linux/linux-
one.html](http://www-03.ibm.com/systems/z/os/linux/linux-one.html)

------
jwildeboer
I wonder if the KVM on zSeries thingy is actually open source and upstream.
From what I can see they (IBM) say it's "based on open source" which is market
droid speak for "actually it's not that open".

~~~
monocasa
It appears to be pretty open source.

[http://lxr.free-electrons.com/source/arch/s390/kvm/](http://lxr.free-
electrons.com/source/arch/s390/kvm/)

------
sgt
When would this type of thing become cost effective? Let's say if you compare
it with your typical X amounts of Dell servers also capable of running 8,000
virtual machines.

------
bluedino
At the last user conference for some iSeries-based software that we run, IBM
had a booth where they displayed a 2U server with dual 16-core Power7 CPUs.
They bragged that it only ran Linux and would save us a ton of money. They
started out at about $20,000 US.

How small is this market? You'd have to have apps that were written to take
advantage of Power7. Equivalent x86 Linux servers are 1/4 the price.

~~~
thoughtpolice
I think the horsepower on those machines shouldn't be underestimated, because
they are not entirely as equivalent as you think... I was thoroughly surprised
when an unoptimized (but correct!) ChaCha20/8 implementation I wrote on a
3.0GHz POWER8 little-endian machine was about as fast as the latest 3.5gHz
Xeons @ AES-256 with AESNI (about 1.3cpb vs 1.0cpb IIRC, but the latter has a
dedicated hardware unit for it!) On that same Xeon, the ChaCha20 code only hit
somewhere around 5cpb - that's software vs silicon!

It also has 170 cores and was actually a QEMU instance (w/ hardware
virtualization extensions) vs raw dedicated metal. If you're doing any kind of
numerical or analytic workloads (even databases), I wouldn't throw them aside
so quickly. You can even get CUDA for them these days, and certain physical
addons like CAPI allow you to map and coherently share physical CPU address
space with FPGAs or GPUs. If I could get those things in a reasonable
workstation configuration, I'd probably go for it tbh.

(I'd be more than willing to repeat this and post some more accurate numbers
if anyone cares. I also need to get around to benchmarking AESNI vs that
POWER8 machines _actual_ dedicated AES unit. The benchmark above was only
flexing its vector/integer unit capabilities. ;)

~~~
ajross
If you're getting a 4x difference in IPC using a crypto microbenchmark from
compiled C code (i.e. it doesn't sound like you're bandwidth or I/O limited),
there has to be something else at work. POWER8 is a nice core, but it's not
_that_ wide. Maybe the compiler was recognizing your operations and replacing
them with AES primitives?

~~~
rdtsc
Caches and memory latency/bandwidth can have serious effects as well.

~~~
ajross
Yes, but at this kind of multiplier only in the case where the entire test is
100% cache-resident on one CPU and spilling on the other. Crypto stuff tends
to have small working sets, so my intuition is that it's got to be something
else.

------
dang
Also
[https://news.ycombinator.com/item?id=10071679](https://news.ycombinator.com/item?id=10071679).

------
ilaksh
How much does the 8000 core thing cost?

~~~
nickpsecurity
Yeah, I'd _really_ like to see that number. I bet it's so big that it's highly
negotiable and still highly profitable. ;)

------
stefantalpalaru
> (The story was refiled to correct the name of the server to "Emperor" from
> "Empire" in paragraph 4 and names of software to "MariaDB" and "PostgreSQL"
> from "Maria" and "Posture" in paragraph 5)

These are the journalists specialized in IT news for a giant like Reuters?

~~~
zymhan
As I read the bit about the correction, I figured Empire and Maria were
understandable mistakes to make. But what in the hell is posture.

Also, I know this is a newswire/business site, but this is super skimpy on the
details.

~~~
chops
Autocorrect? My phone corrects postgres to "postures".

