Category: kubernetes

Abstract grid of glowing compute cells densely packed into reserved cluster capacity

Spark on Kubernetes Reserves CPU It Never Uses. Here’s the Overcommit Fix.

Spark sets executor CPU requests equal to limits, so a Kubernetes cluster reserves twice the CPU it uses and refuses to schedule pending pods. Kubernetes has no native overcommit. Here is the mutating-webhook operator I use to fix it.

By Julien Laurenceau, 5 months2026-05-31 ago

Three open hard drives side by side, the third one on fire: the failure every Kubernetes PVC backend has to plan for

ceph

Choosing the Right Storage Backend for Kubernetes PVCs

Four open source Kubernetes PVC backends compared: Ceph RBD, OpenEBS Local PV ZFS, Mayastor and DRBD with LINSTOR. Whether the application already replicates decides the choice; Ceph RBD brings snapshots and backups, but its multi-site mirroring is not production-ready, unlike Ceph RGW multi-site.

By Julien Laurenceau, 11 months2025-12-15 ago