A two-node Proxmox cluster is a special case: it cannot support native high availability (HA) without a third quorum vote. However, you can still build a resilient and practical storage setup depending on your budget and goals.
Key Principles for a 2-Node Proxmox Setup
- No quorum = no HA failover. You must add a QDevice or a third small node (can be low-power) to act as a quorum voter.
- For HA with shared storage, both nodes must access the same storage.
Ideal Storage Architectures for 2 Nodes
Option 1: Add QDevice + Ceph (Best Long-Term)
- Add a third small node (e.g., Raspberry Pi, Intel NUC, VM) as a QDevice.
- Set up Ceph across the 2 Proxmox nodes.
- Use 3x replication.
- Third node is only for quorum, not storage.
Pros:
- HA works (with QDevice or 3rd node)
- Fully distributed, resilient storage (no SPOF)
- Great for VM disk storage
Cons:
- Complexity
- Needs 3 machines for full HA (even if one is small)
Option 2: External ZFS Storage via NFS or iSCSI
- Run TrueNAS, ZFS-on-Linux, or similar on a dedicated NAS/server.
- Share storage to both Proxmox nodes over NFS or iSCSI.
- Add a third device as QDevice for quorum.
Pros:
- Simpler than Ceph
- Easy ZFS snapshots & replication
- Compatible with HA if quorum is achieved
Cons:
- Shared storage becomes a single point of failure (unless the NAS is clustered)
- NFS has more latency than block-based iSCSI
Option 3: ZFS Replication (No Real HA, but Good Redundancy)
- Each node has local ZFS pools
- Use Proxmox built-in ZFS replication for VMs
- No live migration or HA; failover is manual but fast
Pros:
- Simple, no shared storage
- ZFS benefits: checksums, compression, snapshots
- Works well for small setups or labs
Cons:
- No automatic HA
- Replication is asynchronous (last-minute data may be lost on failover)
Example Configurations
| Setup | Nodes | Storage Type | HA Capable? | Notes |
|---|---|---|---|---|
| Ceph + QDevice | 2 + 1 | Ceph RBD | Yes | Best choice for future scalability |
| NFS/iSCSI + QDevice | 2 + 1 | Shared NAS | Yes | Simpler, cheaper |
| ZFS Replication | 2 | Local ZFS | No | Manual failover only |
Networking and Disk Recommendations
| Component | Spec |
|---|---|
| Network | Dual 1–10 GbE (bonding or separate cluster/storage nets) |
| Disks | SSD/NVMe for VM pools, RAIDZ1/RAID10 on ZFS |
| QDevice | Small VM or Pi with corosync-qdevice |
| Backup | Proxmox Backup Server (PBS) recommended |
Summary: What’s Ideal for You?
- For real HA: Use shared storage (Ceph or NFS/iSCSI) + QDevice
- For budget-friendly: Use ZFS on each node + ZFS replication
- To enable HA at all: Always have a 3rd node or QDevice for quorum
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