4 ms·

I was referring to mainframe migrations, sorry that wasn’t clear.

• jiggawatts 2y ago
  I watched two such mainframe to “modern” architecture transitions recently, one at a telco and one at a medical insurance company. Both replaced what were billing and ERP systems. Both used Java on Linux virtual machines using an n-tier service oriented architecture. Both had a mix of batch and interactive modules. Both suffered from the same issue, which is actually very common but nobody seems to know: power efficiency throttling of CPU speeds. The irony was that the new compute platform had such a huge capacity compared to the old mainframe (20x or more) that the CPUs were only about 1% utilised. The default setting on all such servers is to turn cores off or put them into low-power modes as slow as 400 MHz. This murders performance and especially slows down the network because of the added latency of cores having to wake up from deep sleep when a packet arrives. It was one of those situations where running a busy-loop script on each server would speed up the application because it keeps everything “awake”. The telco doubled their capacity as an attempt to fix the issues but this took them to 0.5% utilisation and things got worse. The health insurer also overcomplicated their network, building a ~100 server cluster as if it was the public cloud. They had nested VLANs, address translation, software defined networking, firewalls between everything, etc… Latency was predictably atrocious and the whole thing ran like it was in slow motion. They too had the CPU throttling issue until I told them about it but the network was so bad it didn’t fix the overall issue.