[chaxor]

I'm lost in this thread.

This whole time I just thought mainframe was an older style word for a large rack based server or server room. Like 'cloud' storage for someone's computer running miniserve.

What is the real difference between a mainframe and, e.g. a rack full of H100s, or rack full of 100GBps networking stuff, or some nice stack of 12x blades with 8x 256 core CPUs?

Why or how does a "mainframe" have more power than that?

[zie]

Mainframes deliver reliable uptime. They so far are the only ones that can do it reliably, for decades.

Essentially the bunch of boxes model(k8s being the new kid on the block) has been trying (and mostly failing) to provide what mainframes have been providing for 60+ years.

Which is being able to treat your workloads as just a random virtual job you can push wherever and let it run while also giving you ridiculous uptime.

Mainframes are basically the hardware infused uptime deliver machines. They can and will offer 5 9's without any trouble. AWS, Azure, Google's cloud, none of them can deliver that amount of uptime, they ALL have failed repeatedly, so much so, that they purposely try to obfuscate their downtime records. Many don't make any historical data available.

k8s and the like have been trying and failing at reliable uptimes. Sure we've arguably been making some progress, but your average self-hosted k8s team has full-time dedicated teams of people that do nothing but babysit k8s. How many staff do your average mainframe org dedicate to keeping the mainframe alive? Usually 1 person, maybe two. Of course the price you pay IBM or whoever you choose as a mainframe provider will help offset the staff savings from your k8s team :)

It's not about raw compute power. It's about keeping a workload alive for as long as you can deliver power to the mainframe. i.e. the Mainframe promises to deliver uptime for as long as you can keep power to the machine. As parts fail, seriously any part: memory, CPU's, disks, backplanes, it doesn't matter. Mainframes can route around the failed part and you can replace it without turning anything off or affecting your workload. This means your mainframe is sized larger than your workload of course. It's not like the fundamentals of compute change in that regard.

The question then becomes, is the juice worth the squeeze? If your entire business model requires uptime, then you best really, really care about uptime. There is a reason the Visa and Mastercard networks have basically never, ever been down. It's because they know their business only exists as long as their network works. When you want uptime at all costs, you don't run k8s(or whatever the latest craze is tomorrow), you run a mainframe.

Most of us get more uptime than we need with insert favourite cloud provider here. Uptime isn't something they actually sell when you read the contracts you sign. Uptime is just marketing spam.

[justinclift]

> They so far are the only ones that can do it reliably, for decades.

AFAIK VAX's are still around, though good luck trying to buy a brand new one. ;)

[zie]

VMS still exists and is ported to x86! :)

I should point out, I was talking about mainframes in general, to include Vaxen, Fujitsu, Unisys, etc. IBM isn't the only mainframe game in town.

[justinclift]

The term "mainframe" has never included Vax's. Not sure why you're trying add it now. ;)

[zie]

The VAX9000 was the end of their mainframe line of VAX machines: https://en.wikipedia.org/wiki/VAX_9000

[sillywalk]

That was a disaster for DEC. It cost $Billions to develop and was barely faster than an NVAX that fit into a desktop case.

[justinclift]

Oh wow, hadn't heard of that. I'd only heard of them doing minicomputers.

That being said, from that their mainframe effort didn't last long.

So they're not a mainframe vendor any more. Their minicomputers were reliable across decades, rather than their mainframes. ;)

[Thaxll]

You oversell mainframes, not sure why you're mentioning k8s but Google which brings 10x more money than visa and MasterCard combined does not use mainframes at all but k8s or equivalent and yet they don't have downtimes either.

With k8s on a major cloud provider you get 99.99% for what? 150$/month? And there is no maintenance what so ever.

Full team managing k8s is a lie, even on prem, what exactly there is to manage on a daily basis?

[zie]

You are talking about hosted k8s, which is not what I'm talking about. If you have never worked on a on-prem k8s team, you are totally missing out! :)

k8s is brittle, all the other competing tools are also fairly brittle, so it's not like k8s is really alone here. This is why we keep replacing the newest mess of virtualization every once in a while, someone eventually gets fed up with whatever the current crap is and writes a new one. It becomes popular, breaks in new and unique ways, rinse and repeat.

k8s is not even a decade old at this point. Mainframes have been around with 5+ 9's of reliability for 6+ decades.

I'm not overselling what mainframes provide. I think you just have selective memory.

99.99% is not what Mainframes provide, they provide many more 9's than that think 7+.

Most of us don't even need 99.99% uptime, so most of us probably shouldn't be buying mainframes. If you DO need severe uptimes, then you either have a huge oversubscription and dedicated teams of people around the clock babysitting things or you buy into mainframes. You absolutely don't buy AWS or Google Cloud or Azure and say, that's good enough, because their uptimes are just marketing speak, not reality.

[Keyframe]

Even if it were true what you're saying, z16 for example targets different needs. Can you scale up to seven or eight nines, and even if you could - could you for same price? That's 3 seconds or 300 milliseconds of downtime per year, reliably. Along with predictable high performance (vertical), hotswap anything including memory, resilience with hardware under provisioning, etc. That's what these beasts are for.

[awesomeMilou]

> With k8s on a major cloud provider you get 99.99% for what? 150$/month? And there is no maintenance what so ever.

Gross understatement of costs don't you think? Last time I checked it was a base fee of 150$/month for managed k8s + whatever computing resources you end up using.

[andyferris]

I think a lot of people might say only IBM sells mainframes - the “z” system.

It’s designed to work as a single high-availability machine with a focus on I/O speeds, rather than a PC cluster that implements high availability at the application level and communicates over IP. You can hot swap faulty components without turning it off. I haven’t ever used one, but I believe you write application code without worrying about such details - the hardware and the libraries you link against will just “make it work”.

Perhaps my knowledge is slightly off though.

[rcbdev]

Many companies also still rock Fujitsu or Unisys mainframes - IBM isn't the only player in this town. But at least Fujitsu's mainframe EOL is in 2035, so that won't be more than historical trivia soon.