Lakshya

Book

Infrastructure & Reliability

Reliability and error budgets, capacity arithmetic, networks, storage and the restore you have not tested, the physical layer, a debugging method that transfers, running production, and an honest look at Kubernetes. Plus a Middleware section — web and application servers, messaging (IBM MQ, Kafka) and managed file transfer, from basics to licensing and cost.

For the Platform, IT Infrastructure and SRE archetypes — and for anyone whose interview will involve designing a system with numbers attached.

Section

Reliability, operations & platforms

CHAPTER 1 What actually makes a system reliable Not uptime. A shared, written definition of acceptable, and a budget for spending the rest. CHAPTER 2 Capacity, and the cost of being wrong in each direction Under-provision and you fail. Over-provision and you fund nothing else. The arithmetic is learnable in an afternoon. CHAPTER 3 Networks, without the certification The layer everything blames and almost nobody measures properly. Six mechanisms explain most of what you will meet. CHAPTER 4 Storage, durability, and the restore you have not tested A backup that has never been restored is a hypothesis. This chapter is about turning it into evidence. CHAPTER 5 The physical layer, and why AI broke the datacentre Power, cooling and space. Unfashionable, non-optional, and currently the binding constraint on the entire industry. CHAPTER 6 Debugging that transfers One method, applied to every resource. It turns troubleshooting from intuition into a checklist you can hand to someone else. CHAPTER 7 Running production Change, incidents and toil. The three things that consume an operations team, and what to do about each. CHAPTER 8 Chaos engineering and game days Controlled experiments on a running system, the human rehearsal that finds a different class of problem, and how to start without frightening anyone. CHAPTER 9 Kubernetes, honestly What it genuinely solves, what it costs, and the four things that break in production. CHAPTER 10 Linux performance: the method, and the six numbers that lie to you A ten-minute checklist that beats an hour of guessing, and the metrics whose ordinary interpretation is wrong. CHAPTER 11 Kubernetes, actually Not the tutorial. The control loops, the scheduler's real algorithm, and why your pod is Pending. CHAPTER 12 Observability: what to instrument, and the bill you will get Three signals, one cardinality trap that has bankrupted monitoring budgets, and the difference between a dashboard and an answer. CHAPTER 13 The observability tool landscape What each product is genuinely for, what it is genuinely bad at, and the licence and pricing history that explains why the market looks like this. CHAPTER 14 OpenTelemetry, and what it does not solve The signal-by-signal maturity people overstate, why the Collector is the real prize, and the problem OTel deliberately left untouched. CHAPTER 15 The observability bill, and why cardinality is the cause A new label multiplies rather than adds, sampling loses either the rare or your budget, and every migration case study has the same fatal confound. CHAPTER 16 AI in observability, honestly What works and why, the benchmark that bounds root-cause claims, and the longitudinal number that went the wrong way. CHAPTER 17 The Kubernetes ecosystem, layer by layer The controller in half of all clusters that is now unmaintained, the licence story everyone reports wrongly, and the mesh adoption number that halved. CHAPTER 18 Managed Kubernetes, and whether you should run it at all Where the three providers genuinely differ, the pricing myth about the serverless tier, and the honest threshold for adopting any of it.
Section

Middleware

Start here — what middleware is, who runs it, and why our job corpus cannot see it
CHAPTER 19 Middleware: the layer between the application and everything else What the word actually covers, the three families a bank runs, who owns them — and why a job corpus built from technology companies cannot see any of it.
Web — web servers, reverse proxies and application servers
CHAPTER 20 Web servers, reverse proxies and application servers, from zero What happens between a customer pressing Log in and a database being asked a question — the tiers, the pools, and the two settings that decide whether the estate survives a busy morning. CHAPTER 21 The web tier in a bank: real flows, real failures Internet banking, partner APIs and staff applications traced through the tiers — the four failures behind most incidents, how patching is done without an outage, and the javax-to-jakarta migration every Java estate is working through. CHAPTER 22 Web and application server products, and the infrastructure under them Who makes what, which of them a bank actually runs, and how to size an estate from a request rate rather than from a vendor’s reference architecture. CHAPTER 23 Web middleware licensing, costs and the comparison Per socket, per core, per virtual core, per employee — four ways to be charged for the same Java workload, one server priced four ways, and the comparison table an interviewer expects you to reason from.
Messaging — message queues, IBM MQ, Kafka and the broker market
CHAPTER 24 What a message queue is, and why banks cannot live without one From a phone call to a posted letter: what asynchronous means, what a broker actually guarantees, and the vocabulary — queues, topics, acknowledgements, dead letters — that every other messaging chapter assumes. CHAPTER 25 IBM MQ from the inside Queue managers, channels, transmission queues and units of work — how IBM MQ moves a payment between two data centres exactly once, the high-availability options from a pair of servers to a mainframe coupling facility, and the reason codes every MQ interview asks about. CHAPTER 26 Kafka and IBM MQ: a log is not a queue The comparison bank messaging interviews ask most: why a log that remembers differs from a queue that forgets, what Kafka’s ‘exactly once’ does and does not cover, and what changed when Kafka learned to queue in February 2026. CHAPTER 27 Real-time banking on messages: six flows, traced A cross-border payment, a domestic high-value transfer, a channel talking to the core, a mainframe read model, a customer alert and a fraud score — each traced through the messaging layer, with what breaks in each and the controls that stop it. CHAPTER 28 The broker market: products, clouds, and the infrastructure under them IBM MQ, Kafka and its distributions, RabbitMQ, the two ActiveMQs, TIBCO, Solace, Pulsar and the cloud queues — who owns what in 2026, what each is genuinely for, and how to size and run one in production. CHAPTER 29 Messaging licences, costs and the comparison IBM MQ’s published prices and its sub-capacity trap, Confluent’s unit pricing, what ‘free’ Kafka and RabbitMQ really cost, the cloud queues’ per-request model — one workload priced six ways, and the product comparison.
File transfer — managed file transfer, and the payment flows that still run on files
CHAPTER 30 Managed file transfer, from zero: why banks still move files Why the batch file survived the API era, what FTP got wrong, what SFTP fixed, and what the word ‘managed’ adds — checkpoints, encryption at rest, audit, partners and schedules. CHAPTER 31 Bank file flows: salaries, schemes, statements and the mainframe Corporate host-to-host payments, national scheme files, SWIFT FileAct, overnight mainframe batch and regulatory returns — traced end to end, with the cut-off clock that governs every one and the duplicate file that every bank has paid twice for. CHAPTER 32 The most attacked middleware: MFT breaches and what they teach Accellion, GoAnywhere, MOVEit, Cleo and GoAnywhere again — five mass exploitations of file-transfer products in five years, a central bank among the victims, and the controls that would have limited each. CHAPTER 33 MFT products, infrastructure, licensing and the comparison IBM Sterling, Axway, Progress MOVEit, Fortra’s GoAnywhere and Globalscape, Cleo, Kiteworks, JSCAPE and the cloud services — how an estate is built and sized, why almost nobody publishes a price, one cloud estate costed, and the comparison.