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Co-authored-by: Cursor <cursoragent@cursor.com>
7.4 KiB
7.4 KiB
VM Placement Explanation - Why VMs Don't Need to Be on Both Servers
Date: 2025-11-27
Question: Why are VMs 100-103 required on both servers?
Short Answer
VMs 100-103 are NOT required on both servers. They are deployed once and can run on either node in the Proxmox cluster. The cluster provides high availability through VM migration, not duplication.
Architecture Overview
Current Setup
- Proxmox Cluster: 2 nodes (ML110 and R630)
- VMs 100-103: Deployed on ML110 (can run on either node)
- Shared Storage: NFS (when configured) allows VM migration
How It Works
┌─────────────────────────────────────────────────────────┐
│ Proxmox VE Cluster (hc-cluster) │
│ │
│ ┌──────────────┐ ┌──────────────┐ │
│ │ ML110 │◄───────►│ R630 │ │
│ │ (Node 1) │ Cluster │ (Node 2) │ │
│ │ │ Network │ │ │
│ └──────┬───────┘ └──────┬───────┘ │
│ │ │ │
│ └──────────┬─────────────┘ │
│ │ │
│ ┌─────▼─────┐ │
│ │ NFS │ │
│ │ Storage │ │
│ │ (Shared) │ │
│ └─────┬─────┘ │
│ │ │
│ ┌──────────┼──────────┐ │
│ │ │ │ │
│ ┌────▼───┐ ┌───▼───┐ ┌───▼───┐ ┌───▼───┐ │
│ │ VM 100 │ │VM 101 │ │VM 102 │ │VM 103 │ │
│ │ │ │ │ │ │ │ │ │
│ │ Can run│ │ Can │ │ Can │ │ Can │ │
│ │ on │ │ run on│ │ run on│ │ run on│ │
│ │ either │ │ either│ │ either│ │ either│ │
│ │ node │ │ node │ │ node │ │ node │ │
│ └────────┘ └───────┘ └───────┘ └───────┘ │
│ │
└─────────────────────────────────────────────────────────┘
Key Concepts
1. Cluster = Shared Management, Not Duplication
A Proxmox cluster means:
- Shared management: Both nodes managed together
- Shared storage: VMs stored on shared storage (NFS)
- VM migration: VMs can move between nodes
- High availability: If one node fails, VMs can run on the other
It does NOT mean:
- ❌ Duplicate VMs on both nodes
- ❌ VMs running simultaneously on both nodes
- ❌ Separate VM instances per node
2. VM Placement Strategy
Current Deployment:
- VMs 100-103 are deployed on ML110
- They can be migrated to R630 if needed
- Only one instance of each VM exists
Why Deploy on One Node Initially:
- Simpler initial setup
- ML110 has SSH access configured
- Can migrate later if needed
When to Migrate:
- Load balancing (spread VMs across nodes)
- Maintenance (move VMs off node being maintained)
- Failure recovery (automatic or manual migration)
3. High Availability Options
Option A: Manual Migration (Current Setup)
- VMs run on one node
- Can manually migrate if node fails
- Requires shared storage (NFS)
Option B: HA Groups (Future)
- Configure HA groups in Proxmox
- Automatic failover if node fails
- Requires shared storage and quorum
Option C: Load Balancing
- Distribute VMs across both nodes
- Better resource utilization
- Still one instance per VM
VM Details
VM 100 - Cloudflare Tunnel
- Current Location: ML110
- Can Run On: Either node
- Why: Single instance sufficient, can migrate if needed
VM 101 - K3s Master
- Current Location: ML110
- Can Run On: Either node
- Why: Single K3s master, can migrate if needed
VM 102 - Git Server
- Current Location: ML110
- Can Run On: Either node
- Why: Single Git server, can migrate if needed
VM 103 - Observability
- Current Location: ML110
- Can Run On: Either node
- Why: Single observability stack, can migrate if needed
When You WOULD Need VMs on Both Servers
Scenario 1: Separate Environments
- Dev on ML110, Prod on R630
- Different VM IDs (e.g., 100-103 on ML110, 200-203 on R630)
- Not a cluster, separate deployments
Scenario 2: Load Balancing
- VM 100, 102 on ML110
- VM 101, 103 on R630
- Still one instance per VM, just distributed
Scenario 3: High Availability Pairs
- VM 100 primary on ML110, standby on R630
- Requires application-level HA (not Proxmox)
- More complex setup
Current Architecture Benefits
✅ Advantages of Current Setup
- Simplicity: One deployment, easier management
- Resource Efficiency: No duplicate resource usage
- Flexibility: Can migrate VMs as needed
- Cost: Lower resource requirements
⚠️ Considerations
- Single Point of Failure: If ML110 fails, VMs need migration
- Load Distribution: All VMs on one node may cause resource contention
- Maintenance: Need to migrate VMs for ML110 maintenance
Recommendations
For Current Setup
- Keep VMs on ML110 (where they are now)
- Configure shared storage (NFS) for migration capability
- Test VM migration between nodes
- Monitor resource usage on ML110
For Future Optimization
- Distribute VMs across both nodes for load balancing:
- ML110: VM 100, 102
- R630: VM 101, 103
- Configure HA groups for automatic failover
- Monitor and balance resource usage
Migration Example
How to Migrate a VM
Via Web UI:
- Select VM → Migrate
- Choose target node (R630)
- Start migration
Via CLI:
# Migrate VM 100 from ML110 to R630
qm migrate 100 r630 --online
Via API:
curl -k -X POST \
-H "Cookie: PVEAuthCookie=..." \
-H "CSRFPreventionToken: ..." \
-d "target=r630" \
"https://192.168.1.206:8006/api2/json/nodes/pve/qemu/100/migrate"
Summary
VMs 100-103 are NOT required on both servers. They are:
- ✅ Deployed once (currently on ML110)
- ✅ Stored on shared storage (when NFS configured)
- ✅ Can run on either node in the cluster
- ✅ Can be migrated between nodes as needed
The cluster provides high availability through migration, not duplication. This is the standard Proxmox cluster architecture.
If you need VMs on both servers for a specific reason, please clarify the requirement and we can adjust the architecture accordingly.