Planning & Capacity
How the cluster was sized: CPU/RAM/disk math, memory overcommit on a swapless host, ZFS ARC capping, and the live VM right-sizing that paid for it.
Why size things at all?
It's a home lab. Why not just give every VM "plenty" of everything and move on? Because the const...
The host, and the numbers
The whole lab runs on a single Proxmox host with, roughly: 64 CPU threads ~125 GiB usable RAM A ...
The thing that quietly eats your RAM: ZFS ARC
There's a second tenant on the host besides the VMs: ZFS. ZFS uses a chunk of RAM as a read cache...
Making room: right-sizing live VMs
The cluster needed real memory: a control-plane node, three workers at 24 GiB each, a build runne...
Lessons from sizing this lab
The short version, for anyone doing the same on their own host: Find your binding constraint fir...