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> ... continued to function ~fine during the AWS outage this week. Isn't any given mainframe stuff one backhoe or flood away from its own outage? What's their

> ... continued to function ~fine during the AWS outage this week. Isn't any given mainframe stuff one backhoe or flood away from its own outage? What's their redundancy and DR plan look like? It's not like they have AZ's and regions, more like a warm replica data center, right?

bob1029 1y ago
> What's their redundancy and DR plan look like? I toured a facility that utilized Parallel Sysplex / GDPS CA. This offers true RTO = RPO = 0. You could take a fire axe to any piece of hardware in the building and it would have zero effect. For catastrophic events, the guarantees relax a little bit, but they're still very strong. Someone breaking an entire fiber vault or setting half the datacenter on fire would still not compromise operations in this facility. It's essentially two datacenters in one, much like how an AWS region works with multiple AZs. Each side of the facility is entirely independent. Somewhere inside a mountain in Colorado a 3rd set of machines is passively replicating everything as well. The most resilient mainframe solutions involve a purpose built facility. The cool thing about the mainframe is that it isn't very big. You can get do a lot of damage with what is effectively just 4 racks of hardware. You'll probably have another 10-20 racks worth of HSMs, firewalls, VPN concentrators, UPSes, etc. Most of the infrastructure is to support the mainframe. So, the facility doesn't actually have to be very large. It just needs to be in a really good location and built like a bunker.
- UltraSane 1y ago
  The datacenter my company rents racks in has a IBM mainframe in it along with a rack for storage and a rack for backup. Very clean and also very expensive.
- p_l 1y ago
  The biggest models are same size as biggest IBM Power machines, i.e. 2 four-post racks connected together. You then need liquid cooling connection, power (iirc the racks can contain internal UPS). You're still left with need for storage which can go from a shelf to maaaany racks, related networking gear (ethernet and FiberChannel) and that's it, but a lot of it would be common to any serious enterprise DC.
  - rbanffy 1y ago
    > You then need liquid cooling connection As far as I can tell, they don’t need external water connections. While everything serious is liquid cooled, they have on-rack radiators. The z17 machines are shipped with the cooling circuit sealed, so it doesn’t need to be filled before use. Power consumption is also relatively low because that’s one demand their clients have that they don’t expand much on top of z16. They are very power-efficient machines. My only complaint is that there’s no desktop or desk side version. Using z/OS as a daily driver would be an interesting challenge.
    - p_l 1y ago
      I am not up to date on latest ones, but it used to be that depending on chosen density you could have "air" cooled meaning sealed liquid cooling with on-rack radiators, and denser units with heat exchanger for external cooling loop.

bob1029 1y ago

> What's their redundancy and DR plan look like? I toured a facility that utilized Parallel Sysplex / GDPS CA. This offers true RTO = RPO = 0. You could take a fire axe to any piece of hardware in the building and it would have zero effect. For catastrophic events, the guarantees relax a little bit, but they're still very strong. Someone breaking an entire fiber vault or setting half the datacenter on fire would still not compromise operations in this facility. It's essentially two datacenters in one, much like how an AWS region works with multiple AZs. Each side of the facility is entirely independent. Somewhere inside a mountain in Colorado a 3rd set of machines is passively replicating everything as well. The most resilient mainframe solutions involve a purpose built facility. The cool thing about the mainframe is that it isn't very big. You can get do a lot of damage with what is effectively just 4 racks of hardware. You'll probably have another 10-20 racks worth of HSMs, firewalls, VPN concentrators, UPSes, etc. Most of the infrastructure is to support the mainframe. So, the facility doesn't actually have to be very large. It just needs to be in a really good location and built like a bunker.

UltraSane 1y ago
The datacenter my company rents racks in has a IBM mainframe in it along with a rack for storage and a rack for backup. Very clean and also very expensive.
p_l 1y ago
The biggest models are same size as biggest IBM Power machines, i.e. 2 four-post racks connected together. You then need liquid cooling connection, power (iirc the racks can contain internal UPS). You're still left with need for storage which can go from a shelf to maaaany racks, related networking gear (ethernet and FiberChannel) and that's it, but a lot of it would be common to any serious enterprise DC.
- rbanffy 1y ago
  > You then need liquid cooling connection As far as I can tell, they don’t need external water connections. While everything serious is liquid cooled, they have on-rack radiators. The z17 machines are shipped with the cooling circuit sealed, so it doesn’t need to be filled before use. Power consumption is also relatively low because that’s one demand their clients have that they don’t expand much on top of z16. They are very power-efficient machines. My only complaint is that there’s no desktop or desk side version. Using z/OS as a daily driver would be an interesting challenge.
  - p_l 1y ago
    I am not up to date on latest ones, but it used to be that depending on chosen density you could have "air" cooled meaning sealed liquid cooling with on-rack radiators, and denser units with heat exchanger for external cooling loop.