MESSAGE
| DATE | 2015-11-02 |
| FROM | Ruben Safir
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| SUBJECT | Subject: [Hangout-NYLXS] IBM Linux mainframes
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http://www.theregister.co.uk/2015/11/02/ibm_linux_mainframes/
Old, not obsolete: IBM takes Linux mainframes back to the future
Your KVMs, give them to me
2 Nov 2015 at 16:57, Liam Proven
IBM introduced several significant new elements for its Linux server
stack last month: support for KVM on its z Systems mainframes,
Linux-only models in both the z Systems and Power Systems ranges, and a
new purchasing model.
The most technically interesting new development is mainframe support
for KVM, the Linux kernel’s built-in hypervisor. Although this is just a
new way to access facilities that existing IBM products offer, it may
help drive migration of x86 workloads onto IBM’s highest-end kit.
Big Blue’s big iron already has rich virtualisation offerings. At the
lowest level, the PR/SM facility splits each machine’s resources into
multiple logical partitions (LPARs), each appearing as a separate
machine with a portion of the host’s processing and storage capacity.
Even if the machine’s configured as a single unit, it’s really one LPAR.
Inside an LPAR, you can run a mainframe OS, such as z/OS or IBM’s
“virtual machine OS”, z/VM. (IBM’s virtualisation technology dates back
to 1972 and thus predates VMware and its ilk by decades – meaning that
IBM uses different terminology. In PC parlance, z/VM is a type 1
hypervisor.) Inside z/VM, you can run other mainframe OSs, including
multiple copies of Linux.
The snag is that if you’re coming across from the PC world, z/VM is
significantly different from anything you’re used to, based as it is on
over 40 years of mainframe tradition. One way to avoid that is to run
the Linux kernel straight on the metal of your LPAR, but that
significantly reduces the number of instances you can run and the
flexibility of managing them.
KVM for Linux resolves this – instead of a daunting mainframe OS, you
can use existing techniques to run Linux VMs under Linux itself.
And since Linux on z Systems is just Linux, this also applies to
management and orchestration tools, too, including anything written in
any scripting language supported on the mainframe distros: Red Hat
Enterprise Linux, SUSE Linux Enterprise and most recently Ubuntu.
Keeping up the Linux push are the new z13 mainframes. The LinuxONE range
currently comprises two Linux-only models: the mid-range Rockhopper and
the high-end Emperor. There isn’t really such a thing as an entry-level
mainframe.
Also, note the penguin-themed names – this sort of playfulness was very
much not the style of the IBM of old. The Emperor model can scale up to
10TB of memory and 8,000 VMs.
Meanwhile, over in the world of slightly more commodity kit ... although
Lenovo finalised the purchase of IBM’s x86 server range back in January,
Big Blue does still have its own RISC processor line – the POWER series.
This CPU family is most famous as the basis for the PowerPC chips that
used to power Apple’s Power Macintosh and the xBox 360, but the original
high-end line is very much alive.
The latest iteration is POWER8, and it includes the other interesting
technical development. There’s all the usual “bigger, better, faster
more” stuff that accompanies the launch of any new processor family –
such as the news that version 8 of POWER supports up to eight hardware
threads per core, compared with Intel which can only manage two.
The bigger news, if you know anything about CPU architectures, is
bi-endian operation. Previous generations of POWER processors supported
handling x86-style little-endian data, but code had to be big-endian.
Version 8 supports completely little-endian operation, meaning that x86
code can now be ported with a simple recompile. This should make it a
more attractive proposition to the vast majority of server users who run
plain old PC kit.
Hoping to cash in on this, IBM is now offering Power Systems boxes that
only run Linux – a surprising move given that it has two OSs of its own
for its other Power-based machines: IBM’s Unix, AIX, and IBM System i,
the old OS/400.
Plus, in the fairly unlikely event that you’ve got old big-endian POWER
code or workloads, the Power Systems’ built-in PowerVM hypervisor can
run both types of distro side-by-side on the same machine – and they
support KVM, too.
IBM introduced two new machines: the S812LC and the S822LC.
The S812 can take either a 3.32GHz 8-core CPU or a 2.92GHz 10-core one,
up to a terabyte of RAM and 14 LFF (so, 3.5 inch) drive bays. The S822
doesn’t have all the drive bays – just a pair of SFF (2.5 inch) bays –
but it supports two processor cards and optional nVidia Tesla GPUs for
GPGPU workloads.
The POWER8 processors look to be competitive with Intel chips in
performance terms and porting x86 Linux code to them is easier than for
any previous generation of POWER-based machines.
Support for KVM virtualisation on both Power Systems and z Systems –
including cheaper models that can run only Linux, not any of IBM’s
proprietary OSs – should ease integration pains and mean that tooling
can be brought straight across.
How do you obtain one of these machines? The new RISC servers can be
bought direct, online, from the company. Indeed, IBM’s product page
sports “IBM Web prices”.
At time of writing, this wasn’t available in all countries yet, but it’s
an important step for the 104-year-old company. IBM is trying to prove
that it is, to quote the most recent Terminator movie, “Old, not obsolete.”
A bit like a wrinkly grey-haired T-800, you find yourself rooting for it. ®
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