The IBM POWER8 Review: Challenging the Intel Xeon
by Johan De Gelas on November 6, 2015 8:00 AM EST- Posted in
- IT Computing
- CPUs
- Enterprise
- Enterprise CPUs
- IBM
- POWER
- POWER8
Software Issues
So although the S824 is IBM's benchmark flagship for the scale-out range, the S812L and S822L are the servers that have the best chance at converting the kinds of users currently opt for x86 Xeons:
- Support for Little Endian data
- Best Linux support (Suse, Redhat & Ubuntu)
- (Somewhat) lower power
- 2U form factor which offers decent performance per U
- and probably the most important reason of all: Affordable! ($10k-25k instead of $30-60k)
So yes, the S822L looks like the first worthy alternative since 2010 for the dual Xeon servers. But the S822L did not inherit all the strong points of the typical "Big Blue" servers. The clockspeeds are a bit lower to keep the power consumption in check, and more importantly the LE Linux support is still very young. Sure, POWERLinux has been around for ages, but the software ecosystem was mostly supporting a few Big Endian applications like heavy duty Java servers and SAP.
Let's make the issue at hand a bit more tangible. IBM offers a migration advisor that helps developers to port their applications. That is definitely a good thing, but it also clearly illustrates that building a software ecosystem is a lot more cumbersome than the POWERPoint slides let you believe. In case of IBM's LE Linux, porting the rich x86 Linux software ecosystem to OpenPOWER is not that straightforward:
- Some code has inline x86 assembly such as thread resource locking code.
- Some code has x86 specific APIs
- No support for POWER in the make files which makes recompiling not straight forward
- POWER is 64 bit only.
We have experienced ourselves that this was more than just theory.
Case in point: for X86-64 we simply installed well tuned, ready to run, pre compiled binaries. Benchmarking is pretty easy here with a minor scripting effort.
The story was very different on the IBM S822L. We installed Ubuntu 15.04 (3.19.0-15 - ppc64le). To satisfy our curiosity we did a quick benchmark run with Linux-Bench, an automated benchmarking tool that Ian also likes to use. The benchmark did almost nothing on our POWER system despite the fact that most of the software had some form of support for POWER based systems.
The same was true for most software out there: We had to port most of the software by delving deep in all kinds of config, Readme, and make files. In many cases, we had to search around for alternative libraries that did support OpenPOWER.
Although a lot of software had an entry for "IBM POWER" in the make files, we encountered a lot of trouble. The server nor IBM is to blame: it is simply a fact that most developers - especially those with HPC software - have put a lot more effort in optimizing and validating their Intel x86 version of their software than the more "exotic" platforms.
Linux Ecosystem Not at Full Throttle.. Yet
It is clear to us that the OpenPOWER Linux ecosytem is still young and as a result does not offer the same performance as the older PowerVM and AIX platforms. There is still quite a bit of performance headroom.
A good example is the crypto acceleration. The IBM POWER8 has a dedicated cryptographic unit supporting new POWER ISA instructions to accelerate AES (Encryption), SHA (Hashing), and CRC (Cyclic Redundancy Check) codes. A similar encryption unit was already available in the POWER7+ . We found out that an nx-crypto driver was available and part of the Linux 3.5 kernel. However, even though Ubuntu 15.04 LE for OpenPOWER is based upon the Linux kernel 3.19, the nx-crypto driver was nowhere to be found. You could argue that the same is true for Intel as they introduce new instructions, but as far as we could see, there was no encryption acceleration whatsoever possible, not even based upon the older POWER7+.
A few days after we have finished testing, we found out the vmx-crypto driver will be available in distributions using the Kernel 4.1 and later and will be enabled in OpenSSL 1.0.2 (currently 1.0.1f in the standard repositories). The slide below - found in a presentation given this month - show how fast the ecosystem is expanding but also that it is still in flux.
OpenPOWER gained traction in 2014, the POWER8 is the first POWER chip with LE support and the number of Linux servers on top of OpenPOWER systems is still very small compared to x86. It is pretty simple: it is a much smaller community than the x86 linux server community. According to "the platform", IBM claims that "scale-out POWER8 machines have seen double digit revenue growth in the first half of 2015" but those growth numbers are "against a very small base". That tells us a lot: it is indeed a very small community, but a quickly growing one.
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psychobriggsy - Friday, November 6, 2015 - link
So you are complaining that your job's selection of hardware has made you earn twice as much?dgingeri - Friday, November 6, 2015 - link
No, because I don't earn twice as much. I'm not fully trained in AIX, so I have to muddle my way through dealing with the test machines we have. We don't use them for full production machines, just for testing software for our customers. (Which means I have to reinstall the OS on at least one of those machines about every month or so. That is a BIG pain in the behind due to the boot procedure. Where it takes a couple hours to reinstall Windows or Linux, it takes a full day to do it on an AIX machine.)I'm trying to advise people to NOT use AIX. It's an awful operating system. I'm also advising people NOT use IBM Power based machines because they are extremely aggravating to work on. Overall, it costs much more to run IBM Power machines, even if they aren't running AIX, than it does to run x86 machines. The up front cost might look competitive, but the maintenance costs are huge. Running AIX on them makes it an order of magnitude more expensive.
serpint - Friday, November 6, 2015 - link
I suggest reading the NIM A-Z handbook. It shouldn't take you more than 10 minutes to fully deploy an AIX system fully built and installed with software. As with Linux, it also shouldn't take more than about 10 minutes to install and fully deploy a server if you have any experience scripting installs.The developerworks community inside IBM is possibly the best free resource you could hope for. Also the redbooks.ibm.com site.
Compared to most *NIX flavors, AIX is UNIX for dummies.
agtcovert - Tuesday, November 10, 2015 - link
If you had a NIM server setup and were using LPARs, loading a functional image of AIX should take 10 minutes flat, on a 1G network.If you're loading AIX on a physical machine without using the virtualization, you're wasting the server.
agtcovert - Tuesday, November 10, 2015 - link
I've worked on AIX platforms extensively for about the same amount of time. First, most of these purchases go through a partner and yours must've sucked because we got great support from our IBM partner -- free training, access to experts, that sort of thing.Second, I always love the complaining about the cost of the hardware, etc. If you're buying big iron Power servers, the maintenance cost should be near irrelevant. And again, your partner should take care to negotiate that into the deal for 3-5 years ensuring you have access to updates.
The other thing no one ever talks about is *why* you buy these servers. Why do they take so long to boot? Well, for the frame it self, it's a deep POST. But then, mine were never rebooted in 4 years, and that's for firmware upgrades (online) and a couple of interface card swaps (also done online with no service disruption). Do that on x86. So reason #1 -- RAS, at the hardware level. Seriously, how often did you need to reboot the frame?
Reason #2 -- for large enterprises, you can do so much with these with relatively few cores they lead to huge licensing savings in Oracle, IBM software. For us, it was over $1m a year ongoing. And no, switching to other software was not an option. We could run an Oracle RAC on 4 cores of Power 7 (at the time) versus the 32 x86 it was on previously. That saves a lot of $.
The machine reviewed does not run AIX. It's Linux only. So the maintenance, etc. you mention isn't even relevant.
There are still things that are annoying I suppose. AIX is steeped in legacy to some degree, and certainly not as easy to manage as a Linux box. But there are a lot of guides out there for free -- it took me about a month to be fully productive. And the support costs you pay for -- well, if I ran into a wall, I just opened a PMR. IBM was always helpful
nils_ - Wednesday, November 11, 2015 - link
I'm mostly working in Linux Devops now, but I remember dreading to use all the "classic" Unix machines at my first "real" job 12 years ago. We ran a few IRIX and AIX boxes which were ancient along itself. Hell even the first thing I did on my work Macbook was to replace the BSD userland with GNU wherever possible.It's hard to find any information on them and any learning materials are expensive and usually on dead trees. They pretty much want to sell training, consulting etc. along with the often non-competitive Hardware prices since these companies don't actually WANT to sell hardware. They want to sell everything that surrounds it.
retrospooty - Friday, November 6, 2015 - link
The problem with server chips is that its about platform stability. IBM (and others) dropped off the face of the Earth and as mentioned above Intel now has 95% of the market. This chip looks great but will companies buy into it in mass? What if IBM makes another choice to drop off the face of the Earth again and your platform is dead ended? I would have to think long and hard about going with them at this point.FunBunny2 - Friday, November 6, 2015 - link
Not likely. the mainframe z machines are built using POWER blocks.Kevin G - Friday, November 6, 2015 - link
POWER and System Z are two different architectures. Case in point, POWER is a RISC design introduced in the 90's where as the System Z mainframes can trace their roots to a CISC design from the 1960's (and it is still possible to run some of that 1960's code unmodified).They do share a handful of common parts (think the CDIMMs) to cut down on support costs.
plonk420 - Friday, November 6, 2015 - link
can you run an x264 benchmark on it?? x)