# Sre
All Sre notes →1 — Virtual Machines
The hypervisor-level isolation and resource accounting that containers still inherit assumptions from, and where VM-level failure domains differ from container ones.
10 — Multi-Region Deployments
Active-active vs. active-passive across regions, and the data-replication latency that ultimately caps how 'active' active-active can really be.
11 — Infrastructure as Code
Why declarative infra state, not scripts, is what makes an environment reproducible — and the drift between declared and actual state that erodes that guarantee over time.
12 — Immutable Infrastructure
Replacing instead of patching running infrastructure, and why it turns configuration drift from a chronic failure mode into one that mostly can't happen.
13 — GitOps
Git as the single source of truth for cluster state, and the reconciliation loop that makes 'what's actually running' a query instead of a guess.
14 — Configuration Management
Where config lives, how it's validated before rollout, and why a bad config push is still one of the most common root causes of a full-severity incident.
2 — Containers
Namespaces and cgroups as the actual mechanism behind 'containers,' and why a container's reliability characteristics are really the host kernel's.
3 — Kubernetes Fundamentals
The control-plane/data-plane split and reconciliation-loop model that everything else in Kubernetes — scheduling, networking, storage — is built on top of.
4 — Kubernetes Scheduling
How the scheduler turns resource requests, affinity rules, and taints into a placement decision, and why a 'Pending' pod is almost always a scheduling constraint, not a mystery.
5 — Networking in Kubernetes
The CNI, Service, and kube-proxy layers that turn a flat pod network into something with DNS names, load balancing, and — inevitably — new failure modes.
6 — Storage in Kubernetes
PersistentVolumes, StorageClasses, and the CSI driver layer, and why stateful workloads are still the hardest thing to run reliably on Kubernetes.
7 — High Availability Clusters
Multi-master control planes, etcd quorum, and the failure domains that determine whether a single zone outage takes the whole cluster with it.
8 — Autoscaling
HPA, VPA, and cluster autoscaling, and why autoscaling on the wrong signal turns a capacity problem into a cascading one instead of solving it.
9 — Multi-Cluster Architectures
Why teams split a single Kubernetes footprint into multiple clusters — blast radius, compliance, scale limits — and the fleet-management cost that decision buys.