Zabbix Agent Active vs Passive: What They Mean and When to Use Each
TL;DR How Active Works How Passive Works Quick Comparison Aspect Active Passive Connection Agent → Server :10051 Server → Agent
Observability & Operations
Engineering field notes
Practical DevOps & Infrastructure Notes
Tested guides for Linux, cloud, containers, and self-hosted services.
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Cloud, Linux & Virtualization
Create a KVM VM on Ceph RBD
This follow-up shows the cleanest, minimal path to put a Libvirt/QEMU VM disk on Ceph RBD and create the VM
Cloud, Linux & Virtualization
Ubuntu 24.04: Full Cold Backup of KVM/Libvirt with rsync
TL;DR: Power off all VMs → (optionally) stop or mask libvirt sockets so nothing auto-starts → rsync both /etc/libvirt and
Cloud, Linux & Virtualization
Build ccache 4.11.3 from Source on Ubuntu 24.04
Goal: Compile and install ccache v4.11.3 from source on Ubuntu 24.04, with manpages. Includes expected install output, sanity checks, and
Cloud, Linux & Virtualization
Install the Latest Ansible on Ubuntu 24.04 with apt, Bootstrap Remotes, and Run a Minimal Project
Scope: apt-install Ansible, create an ansible user on the controller, provision remotes, and run a small project. 1. Install Ansible
Networking & Connectivity
Custom DDNS for Your Home Lab with Cloudflare (Python + cron)
Goal: keep a hostname (e.g., home.maksonlee.com) always pointing to your current WAN IP by calling Cloudflare’s API on a schedule.
Data Platforms & Analytics
Global Reset: Cassandra CDC → Debezium → Kafka (SASL/SSL via HAProxy) → Spark → Delta Lake
Scope: wipe & rebuild the full ThingsBoard data pathKeyspace: thingsboard (drop + recreate)Kafka topics: tb.thingsboard.ts_kv_cf, tb.thingsboard.ts_kv_partitions_cf (auto-create enabled)Delta root: /delta
Identity, Security & PKI
Root CA, Intermediate CA, Server Certificates, and Private Keys Explained
When setting up TLS for your own services, or working with certificates from a commercial Certificate Authority, you will encounter
Data Platforms & Analytics
Fixing Huge /var/log/syslog Caused by Debezium Cassandra Connector
When I followed my earlier guide End-to-End Stream: Cassandra 5.0.5 CDC → Kafka 4.0 (SASL/SSL) → Spark 3.5.6 → Delta
Data Platforms & Analytics
Set Cassandra 5.0 JVM Memory Limits on Ubuntu 24.04 (Java 17)
Goal: make Cassandra’s memory use predictable by pinning the JVM heap and (optionally) capping off-heap/direct memory. This guide targets Ubuntu