docs: right-size VM 106 (docker-home) — 16 GB/8 vCPU → 6 GB/4 vCPU (#19)

Pre-checks confirmed safe to right-size: no container --memory limits,
no Docker Compose memory reservations. Live usage 1.1 GB / 15 GB (7%).

- Update 106.conf: memory 16384 → 6144, sockets 2 → 1 (8 → 4 vCPUs)
- Add right-sizing-vm-106.md runbook with pre-check results and resize commands

Closes #19

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server-configs/proxmox/qemu/106.conf

@@ -1,7 +1,7 @@
 agent: 1
 boot: order=scsi0;net0
 cores: 4
-memory: 16384
+memory: 6144
 meta: creation-qemu=6.1.0,ctime=1646083628
 name: docker-home
 net0: virtio=BA:65:DF:88:85:4C,bridge=vmbr0,firewall=1
@@ -11,5 +11,5 @@ ostype: l26
 scsi0: local-lvm:vm-106-disk-0,size=256G
 scsihw: virtio-scsi-pci
 smbios1: uuid=54ef12fc-edcc-4744-a109-dd2de9a6dc03
-sockets: 2
+sockets: 1
 vmgenid: a13c92a2-a955-485e-a80e-391e99b19fbd

server-configs/proxmox/right-sizing-vm-106.md

@@ -0,0 +1,141 @@
+---
+title: "VM 106 (docker-home) Right-Sizing Runbook"
+description: "Runbook for right-sizing VM 106 from 16 GB/8 vCPU to 6 GB/4 vCPU — pre-checks, resize commands, and post-resize validation."
+type: runbook
+domain: server-configs
+tags: [proxmox, infra-audit, right-sizing, docker-home]
+---
+
+# VM 106 (docker-home) Right-Sizing Runbook
+
+## Context
+
+Infrastructure audit (2026-04-02) found VM 106 severely overprovisioned:
+
+| Resource | Allocated | Actual Usage | Target |
+|----------|-----------|--------------|--------|
+| RAM | 16 GB | 1.1–1.5 GB | 6 GB (4× headroom) |
+| vCPUs | 8 (2 sockets × 4 cores) | load 0.12/core | 4 (1 socket × 4 cores) |
+
+**Services**: Pi-hole, Nginx Proxy Manager, Portainer
+
+## Pre-Check Results (2026-04-03)
+
+Automated checks were run before resizing. **All clear.**
+
+### Container memory limits
+
+```bash
+docker inspect pihole nginx-proxy-manager_app_1 portainer \
+  | python3 -c "import json,sys; c=json.load(sys.stdin); \
+    [print(x['Name'], 'MemoryLimit:', x['HostConfig']['Memory']) for x in c]"
+```
+
+Result:
+```
+/pihole MemoryLimit: 0
+/nginx-proxy-manager_app_1 MemoryLimit: 0
+/portainer MemoryLimit: 0
+```
+
+`0` = no limit — no containers will OOM at 6 GB.
+
+### Docker Compose memory reservations
+
+```bash
+grep -rn 'memory\|mem_limit\|memswap' /home/cal/container-data/*/docker-compose.yml
+```
+
+Result: **no matches** — no compose-level memory reservations.
+
+### Live memory usage at audit time
+
+```
+total: 15 GiB  used: 1.1 GiB  free: 6.8 GiB  buff/cache: 7.7 GiB
+Pi-hole:  463 MiB
+NPM:      367 MiB
+Portainer:  12 MiB
+Total containers: ~842 MiB
+```
+
+## Resize Procedure
+
+Brief downtime: Pi-hole and NPM will be unavailable during shutdown.
+Manticore runs Pi-hole 2 (10.10.0.226) for HA DNS — clients fail over automatically.
+
+### Step 1 — Shut down the VM
+
+```bash
+ssh proxmox "qm shutdown 106 --timeout 60"
+# Wait for shutdown
+ssh proxmox "qm status 106"   # Should show: status: stopped
+```
+
+### Step 2 — Apply new hardware config
+
+```bash
+# Reduce RAM: 16384 MB → 6144 MB
+ssh proxmox "qm set 106 --memory 6144"
+
+# Reduce vCPUs: 2 sockets × 4 cores → 1 socket × 4 cores (8 → 4 vCPUs)
+ssh proxmox "qm set 106 --sockets 1 --cores 4"
+
+# Verify
+ssh proxmox "qm config 106 | grep -E 'memory|cores|sockets'"
+```
+
+Expected output:
+```
+cores: 4
+memory: 6144
+sockets: 1
+```
+
+### Step 3 — Start the VM
+
+```bash
+ssh proxmox "qm start 106"
+```
+
+Wait ~30 seconds for Docker to come up.
+
+### Step 4 — Verify services
+
+```bash
+# Pi-hole DNS resolution
+ssh pihole "docker exec pihole dig google.com @127.0.0.1 | grep -E 'SERVER|ANSWER'"
+
+# NPM — check it's running
+ssh pihole "docker ps --filter name=nginx-proxy-manager --format '{{.Status}}'"
+
+# Portainer
+ssh pihole "docker ps --filter name=portainer --format '{{.Status}}'"
+
+# Memory usage post-resize
+ssh pihole "free -h"
+```
+
+### Step 5 — Monitor for 24h
+
+Check memory doesn't approach the 6 GB limit:
+
+```bash
+ssh pihole "free -h && docker stats --no-stream --format 'table {{.Name}}\t{{.MemUsage}}'"
+```
+
+Alert threshold: if `used` exceeds 4.5 GB (75% of 6 GB), consider increasing to 8 GB.
+
+## Rollback
+
+If services fail to come up after resizing:
+
+```bash
+# Restore original allocation
+ssh proxmox "qm set 106 --memory 16384 --sockets 2 --cores 4"
+ssh proxmox "qm start 106"
+```
+
+## Related
+
+- [Maintenance Reboot Runbook](maintenance-reboot.md) — VM 106 is Tier 2 (shut down after apps, before databases)
+- Issue: cal/claude-home#19