# PVE 3-Node HA Cluster for Iron Legion

**Status:** Draft | **Author:** Artemis | **Date:** 2026-06-04

## 1. Objective

Configure MK33, MK34, and MK39 as a Proxmox VE 3-node cluster with shared NFS storage from TrueNAS. Enable manual live migration of VMs/LXCs between nodes, and optionally automatic HA failover for critical workloads.

## 2. Current State

| Node | CPU | RAM | Storage | Role |
|------|-----|-----|---------|------|
| MK33 (Silver Centurion) | Intel N150 4c/4t | 16GB | Local SSD | PVE HA |
| MK34 (Southpaw) | Intel N150 4c/4t | 16GB | Local SSD | PVE HA |
| MK39 (Gemini) | Intel N150 4c/4t | 16GB | Local SSD | PVE HA (spare)
| TrueNAS SCALE | 4c | 11GB | HDD pool | NFS server |

All nodes on `192.168.0.0/18`. TrueNAS at `192.168.16.254`.

## 3. Architecture

### 3.1 Cluster Model: Proxmox 3-Node Cluster (No Ceph)

```
MK33 (192.168.7.33) ──┐
                       ├─ Corosync Ring ── Shared NFS (TrueNAS)
MK34 (192.168.7.34) ──┤
                       │
MK39 (192.168.7.39) ──┘
```

- **Quorum:** 3-node cluster = 2 votes needed for quorum. If one node dies, remaining 2 form quorum.
- **Shared storage:** TrueNAS NFSv4.2 export `/mnt/Ice/Backup`
- **HA manager:** Proxmox HA services (`pve-ha-crm`, `pve-ha-lrm`) for automatic restart

### 3.2 Storage Flow

```
Build on local disk → Test workload → Shutdown → Move disk to NFS → Restart on NFS
                                          ↓
If node fails: HA manager detects → Restarts VM/LXC on surviving node (same NFS disk)
```

### 3.3 Workload Planning

| Type | Count per node | Resources each |
|------|---------------|----------------|
| VM (general) | 1 | 4 vCPU, 4096 MB RAM |
| LXC (lightweight) | 5–10 | 1 vCPU, 512–1024 MB RAM |

**Total per node estimated:** 9–14 vCPUs (but N100 is 4c/4t — LXCs share cores opportunistically via cgroups)
**Total RAM per node:** VM 4GB + 5×1GB LXCs = ~9GB allocated, 7GB headroom

## 4. Pros vs Cons

### 4.1 3-Node Cluster (Recommended)

**Pros:**
- Unified web UI for all 3 nodes from any one node
- Live migration of VMs/LXCs between nodes (zero downtime)
- Automatic HA failover for critical VMs/LXCs
- Quorum maintained with 2 of 3 nodes online
- Shared NFS storage means VMs are portable across nodes

**Cons:**
- Corosync ring traffic adds minor network overhead
- If 2 nodes fail simultaneously, quorum lost, cluster stops
- HA failover is restart (brief downtime), not live migration
- N100 CPU is modest — 3 VMs + 15 LXCs across cluster is tight but workable

### 4.2 Standalone Nodes (Current)

**Pros:**
- Simple, no cluster complexity
- Node failure doesn't affect others
- No Corosync network overhead

**Cons:**
- No live migration — moving a VM requires export/import
- No automatic failover — manual intervention if node dies
- 3 separate web UIs to manage

## 5. Implementation Plan

### Phase 1: Cluster Formation

1. Add all 3 nodes to `/etc/hosts` on each node (or DNS via Technitium)
2. On MK33: `pvecm create iron-legion`
3. On MK34/MK39: `pvecm add 192.168.7.33`
4. Verify: `pvecm status` shows 3 nodes, quorum 2/3

### Phase 2: NFS Storage Setup

1. Ensure TrueNAS exports `/mnt/Ice/Backup` with:
   - NFSv4.2
   - `maproot` or `mapall` to `root` (PVE nodes need root access)
   - ACL allows `192.168.0.0/18`
2. On PVE Datacenter → Storage → Add → NFS:
   - ID: `truenas-backup`
   - Server: `192.168.16.254`
   - Export: `/mnt/Ice/Backup`
   - Content: `images,rootdir`
3. Verify storage shows on all 3 nodes

### Phase 3: HA Configuration

1. Proxmox HA → Add groups:
   - `critical`: nodes mk33,mk34,mk39 (any node)
   - `local-only`: single-node constraint for local-disk VMs
2. For each VM/LXC on NFS storage:
   - Datacenter → HA → Add → Select VM → Group `critical` → Start on any
3. Start fencing daemon if IPMI/ watchdog available (optional for N100)

### Phase 4: Workload Migration Testing

1. Build a test LXC on local storage
2. Migrate disk to NFS: `Move disk` → target `truenas-backup`
3. Verify LXC starts from NFS
4. Test live migration: right-click → Migrate → select target node
5. Test HA failover: power off source node, verify restart on surviving node

## 6. Open Questions

1. Do we need HA fencing? (IPMI not available on N100 — watchdog only)
2. Should we reserve one node as "management" and only run LXCs on two?
3. What's the Tailscale story — do we bind Corosync to LAN only or also Tailscale?

## 7. Decision Points

| Decision | Option A | Option B |
|----------|----------|----------|
| Cluster type | 3-node with quorum (recommended) | 2-node + witness (not recommended) |
| HA level | Manual migration only | Full HA with auto-restart |
| Storage | NFS only (current) | Add local Ceph later |
| Resource reserve | 1 node mostly idle | Distribute evenly |

---

**Awaiting Commander Bobby review and approval.**