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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>

2026-04-03 23:05:43 -05:00

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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

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

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

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

# 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

ssh proxmox "qm start 106"

Wait ~30 seconds for Docker to come up.

Step 4 — Verify services

# 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:

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:

# Restore original allocation
ssh proxmox "qm set 106 --memory 16384 --sockets 2 --cores 4"
ssh proxmox "qm start 106"

Maintenance Reboot Runbook — VM 106 is Tier 2 (shut down after apps, before databases)
Issue: cal/claude-home#19

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