4 ms·

My guess is a mainframe would be much better at handling a high volume of transactions much better than a $50k server? I would also think it would better handle

My guess is a mainframe would be much better at handling a high volume of transactions much better than a $50k server? I would also think it would better handle conditions where "eventually consistent" doesn't work? I'm sure most companies are running batch processes and data-intensive calculations that could be easily shifted to cloud workloads in practice, but it does seem like there are some use cases where a mainframe could be better?

marcosdumay 7y ago
Yes if you have a huge volume of transactions and a huge amount of constraints that can not be partitioned. But the real world constraints can almost always be partitioned. For read-only batch computations you can always add some extra redundancy and partition the problem. So, I don't think it is likely that a mainframe would be useful here.
fhars 7y ago
And it is especially quite a bit better in handling a high volume of transactions while physically replacing one of the CPUs and half of the RAM in the system than many $50k servers.
- wolf550e 7y ago
  You are paying about 100x on hardware because your software is limited to a single address space. Even if the mainframe never goes down, the entire site will go down (eventually the rack power supply, HVAC, fiber, natural disaster, backhoe, etc. will get you even if your CPUs and RAM are redundant and replaced before they fail), and then either your entire business stops or at least processing for that region stops, or your system is resilient to site failure because you built a distributed system anyway. If you could rewrite your software to be distributed and handle a node/site going down, you could run a single site on 5 servers that together outperform the mainframe (by a lot) and can be serviced on a whole server basis (though of course, expensive x86 servers also have reliability features), or use really cheap hardware without even redundant power supplies, but have enough of them to not care. The modern solutions are better than the mainframe, and the only reason to use them is management risk aversion and unwillingness to learn new things.
  - chx 7y ago
    A single mainframe can easily be located in multiple datacenters. The Hungarian state owned electricity distributor company has one, one half is at Budapest the other half -- if memory serves -- is at Miskolc, a bit more than a hundred miles away.
    - wolf550e 7y ago
      Is that a single address space system or merely two systems with db2 databases and disk volumes on a SAN in replication? I think it's the latter. 100 miles will add 5ms (round trip) to your disk flush on commit. So a system like this has the sequential and random IO latencies of a RAID of SSDs but the flush (database commit) times of a 15K RPM spinning rust disk. People lived with mechanical disks, it's ok. Sync disk replication (in one direction) over a fiber line is not an exclusive feature. Having both sides be active, instead of active and hot standby requires some smarts from the software, but modern distributed databases do that, and if you're careful you can get far with batch sync jobs.
      - chx 7y ago
        It might be just storage as it was brought up as an example of how subsystems of mainframes are essentially their own world and a single disk or distributed volumes over a long distance are presented the same to the rest of the system. In the Linux world DRBD does something similar (just much simpler). The point, however, is that the software knows nothing about this being distributed.
wolf550e 7y ago
No. If you need reliability and have money, separate commodity servers running a consistent (paxos or raft, not eventually consistent) in-memory database (the memory is a few terabytes) with logs to flash and to disaster recovery site will outperform a mainframe. A single computer with 4 sockets of xeons will outperform a mainframe but will have more downtime. The mainframe has best possible single thread performance and as much cache as possible, redundancy and parts can be replaced while it's online, but not that many cores. The cost is very high - when I looked, 1 million per year is the baby version with only 1 CPU enabled and no license to run the cryptographic accelerator and limits on software, etc. Commodity hardware you buy and use for 5 years, so the amount of good hardware you can buy for the price of owning a mainframe for 5 years is a lot. For the money, you can buy a lot more CPU, ram, network, storage, etc and hire Kyle Kingsbury to audit your distributed database.
- ch_123 7y ago
  >The cost is very high - when I looked, 1 million per year is the baby version with only 1 CPU enabled and no license to run the cryptographic accelerator and limits on software, etc. At one point, IBM was selling base-level mainframes for $75,000 (see https://arstechnica.com/information-technology/2013/07/ibm-unveils-new-mainframe-for-the-rest-of-us/ https://arstechnica.com/information-technology/2013/07/ibm-u...) It is true though that a 'realistic' configuration is likely to cost north of $1 million, and that none of these numbers include the price of the software.
  - StrangeDoctor 7y ago
    It’s the support contract that’s the real cost.
  - rodgerd 7y ago
    A standard IBM "gotcha" is to offer deep discounts and charge the 20% p.a. maint cost on the list price - e.g. "We'll give you this hardware for $1." then a year later "So sorry the maint is 3 x $250k x 0.2 = $150k p.a.". Another is that the software and hardware designed to turn a baby system into anything useful is astonishingly expensive to people not used to dealing with this end of the market. Enjoy finding that your hypervisor is licensed at 5 figures per core, and that your cores are six figures a pop.

marcosdumay 7y ago

Yes if you have a huge volume of transactions and a huge amount of constraints that can not be partitioned. But the real world constraints can almost always be partitioned. For read-only batch computations you can always add some extra redundancy and partition the problem. So, I don't think it is likely that a mainframe would be useful here.

fhars 7y ago

And it is especially quite a bit better in handling a high volume of transactions while physically replacing one of the CPUs and half of the RAM in the system than many $50k servers.

wolf550e 7y ago
You are paying about 100x on hardware because your software is limited to a single address space. Even if the mainframe never goes down, the entire site will go down (eventually the rack power supply, HVAC, fiber, natural disaster, backhoe, etc. will get you even if your CPUs and RAM are redundant and replaced before they fail), and then either your entire business stops or at least processing for that region stops, or your system is resilient to site failure because you built a distributed system anyway. If you could rewrite your software to be distributed and handle a node/site going down, you could run a single site on 5 servers that together outperform the mainframe (by a lot) and can be serviced on a whole server basis (though of course, expensive x86 servers also have reliability features), or use really cheap hardware without even redundant power supplies, but have enough of them to not care. The modern solutions are better than the mainframe, and the only reason to use them is management risk aversion and unwillingness to learn new things.
- chx 7y ago
  A single mainframe can easily be located in multiple datacenters. The Hungarian state owned electricity distributor company has one, one half is at Budapest the other half -- if memory serves -- is at Miskolc, a bit more than a hundred miles away.
  - wolf550e 7y ago
    Is that a single address space system or merely two systems with db2 databases and disk volumes on a SAN in replication? I think it's the latter. 100 miles will add 5ms (round trip) to your disk flush on commit. So a system like this has the sequential and random IO latencies of a RAID of SSDs but the flush (database commit) times of a 15K RPM spinning rust disk. People lived with mechanical disks, it's ok. Sync disk replication (in one direction) over a fiber line is not an exclusive feature. Having both sides be active, instead of active and hot standby requires some smarts from the software, but modern distributed databases do that, and if you're careful you can get far with batch sync jobs.
    - chx 7y ago
      It might be just storage as it was brought up as an example of how subsystems of mainframes are essentially their own world and a single disk or distributed volumes over a long distance are presented the same to the rest of the system. In the Linux world DRBD does something similar (just much simpler). The point, however, is that the software knows nothing about this being distributed.

wolf550e 7y ago

No. If you need reliability and have money, separate commodity servers running a consistent (paxos or raft, not eventually consistent) in-memory database (the memory is a few terabytes) with logs to flash and to disaster recovery site will outperform a mainframe. A single computer with 4 sockets of xeons will outperform a mainframe but will have more downtime. The mainframe has best possible single thread performance and as much cache as possible, redundancy and parts can be replaced while it's online, but not that many cores. The cost is very high - when I looked, 1 million per year is the baby version with only 1 CPU enabled and no license to run the cryptographic accelerator and limits on software, etc. Commodity hardware you buy and use for 5 years, so the amount of good hardware you can buy for the price of owning a mainframe for 5 years is a lot. For the money, you can buy a lot more CPU, ram, network, storage, etc and hire Kyle Kingsbury to audit your distributed database.

ch_123 7y ago
>The cost is very high - when I looked, 1 million per year is the baby version with only 1 CPU enabled and no license to run the cryptographic accelerator and limits on software, etc. At one point, IBM was selling base-level mainframes for $75,000 (see https://arstechnica.com/information-technology/2013/07/ibm-unveils-new-mainframe-for-the-rest-of-us/ https://arstechnica.com/information-technology/2013/07/ibm-u...) It is true though that a 'realistic' configuration is likely to cost north of $1 million, and that none of these numbers include the price of the software.
- StrangeDoctor 7y ago
  It’s the support contract that’s the real cost.
- rodgerd 7y ago
  A standard IBM "gotcha" is to offer deep discounts and charge the 20% p.a. maint cost on the list price - e.g. "We'll give you this hardware for $1." then a year later "So sorry the maint is 3 x $250k x 0.2 = $150k p.a.". Another is that the software and hardware designed to turn a baby system into anything useful is astonishingly expensive to people not used to dealing with this end of the market. Enjoy finding that your hypervisor is licensed at 5 figures per core, and that your cores are six figures a pop.