When you connect a NAS or storage server to your network, you need a protocol to make that storage accessible to other devices. The three you’ll encounter most often are SMB, NFS, and iSCSI. They solve different problems and suit different environments. Choosing the right one depends on what you’re connecting, and what you need the storage to do.
SMB — Server Message Block
SMB is the native file-sharing protocol for Windows. When you browse to a network share (a \\server\share path), you’re using SMB. It’s also supported on macOS and Linux, making it the most universally compatible option for mixed environments.
SMB presents shared storage as a folder accessible over the network. Multiple users and devices can connect simultaneously and browse, read, and write files independently. Permissions are managed at the share or folder level.
Where SMB fits:
- File shares for Windows workstations and laptops
- Mixed Windows/Mac/Linux environments
- NAS devices serving files to office staff
- General-purpose shared storage
SMB is the right default for most SME file-sharing requirements. It’s well understood, supported everywhere, and straightforward to configure on any modern NAS.
Current version: SMB3 is the current standard, offering improved performance and encryption. SMB1 is a legacy version with serious security vulnerabilities; it should be disabled on all devices.
NFS — Network File System
NFS is the native file-sharing protocol for Unix and Linux systems. It works similarly to SMB in concept: storage on a server is presented as a mountable filesystem to client machines. The difference is the ecosystem. NFS is natively fast and efficient on Linux, and is the standard protocol for Linux-to-Linux storage sharing.
NFS permissions are traditionally managed by IP address or hostname rather than user credentials, which makes it simpler to configure in server environments but less granular than SMB for multi-user desktop environments.
Where NFS fits:
- Linux servers and virtual machine hosts accessing shared storage
- Proxmox or other hypervisors mounting NAS storage for VM files
- Environments where all clients are Linux or Unix-based
For an SME running Proxmox with a Synology NAS providing shared storage for VM images, NFS is typically the preferred protocol. It performs well, integrates cleanly, and is the expected choice in that environment.
iSCSI — Internet Small Computer Systems Interface
iSCSI is fundamentally different from SMB and NFS. Rather than presenting storage as a shared folder, iSCSI presents a storage device: a virtual hard drive (called a LUN, or Logical Unit Number) that appears to the connecting server as if it were a locally attached disk.
The connecting server formats the LUN with its own filesystem and treats it as a local drive. Only one server typically connects to a LUN at a time (with some exceptions using cluster-aware filesystems).
This distinction matters. Because the server sees the storage as a local disk, it can use it for workloads that require block-level storage: Windows Server with NTFS, SQL Server databases, Exchange data stores, Hyper-V virtual machine files.
Where iSCSI fits:
- Windows servers that need to store databases or application data on a NAS
- Hyper-V hosts using shared storage for virtual machine files
- Any workload that requires block-level storage rather than file-level access
- Environments where a single server needs dedicated, high-performance storage
iSCSI requires more configuration than SMB or NFS: initiators on the connecting server, targets on the storage device, and network considerations (iSCSI benefits from a dedicated VLAN or network interface). The payoff is performance and compatibility with workloads that can’t use file-based protocols.
Side-by-Side Comparison
| Protocol | Access type | Best for | Platform |
|---|---|---|---|
| SMB | File-level | Windows file shares, mixed environments | Windows, macOS, Linux |
| NFS | File-level | Linux servers, hypervisor storage | Linux, Unix |
| iSCSI | Block-level | Databases, Hyper-V, Windows server storage | Any (via initiator software) |
Which Should You Use?
For most SME file-sharing requirements, SMB is the right answer. It works everywhere, integrates with Active Directory permissions, and is supported by every NAS platform on the market.
If you’re running Linux servers or a Proxmox hypervisor and want to mount NAS storage for VM files, NFS is the appropriate choice.
If you’re running Windows Server workloads that need block-level storage (SQL Server, Exchange, Hyper-V), iSCSI is worth the additional configuration effort.
In practice, most SME NAS deployments use a combination: SMB for staff file shares, NFS or iSCSI for server and hypervisor storage, all on the same physical NAS device.