1. Quick Overview
NAS (Network Attached Storage) offers shared file-level storage over network protocols like SMB or NFS. SAN (Storage Area Network) offers block-level storage (iSCSI/FC) which servers treat just like local disks.
2. Key Differences at a Glance
Feature | NAS | SAN
----------------------------------------------
Storage Type | File-level (SMB/NFS) | Block-level (iSCSI/FC)
Typical Use Case | Shared files, backups | VM datastores, databases
Performance | Moderate | High (low latency, high IOPS)
Management Complexity | Lower | Higher (zoning, masking)
Costs | $-$-$ | $$-$$$+
3. Why This Matters for IT Architects
Choosing the wrong storage type can drag performance, complicate backup & restore, inflate costs, and slow your overall operations. As an IT professional, understanding NAS vs SAN helps you design systems that match the workload — delivering reliability, speed, and maintainability.
4. What Is NAS?
4.1 Architecture & Protocols
A typical NAS device is a dedicated appliance or server with its own OS (like ONTAP, TrueNAS, QNAP) and uses standard Ethernet networking (1/10/25/100 GbE). Clients connect via SMB or NFS.
Because data is exposed at the file-level, you work with paths like \\NAS-01\Share (Windows) or /mnt/nas/data (Linux).
4.2 Use Cases
- User home directories and file shares
- Media repositories, shared backups
- Small VM labs, dev/test environments
5. What Is SAN?
5.1 Architecture & Protocols
SAN presents storage over a dedicated fabric using iSCSI (Ethernet) or Fibre Channel (FC). Hosts discover LUNs (logical units) and format them as disks (NTFS, ext4, VMFS, etc.).
5.2 Use Cases
- High-performance applications (databases, large VMware clusters)
- Low-latency storage for VDI pools
- Storage that requires multipath, zone isolation, high availability
6. Performance & Reliability Comparison
Here’s how they differ in key metrics:
- Latency: NAS ~1-5 ms (depending on caching, load); SAN ~<1 ms with FC/NVMe fabrics.
- IOPS: NAS supports moderate IOPS; SAN designed for tens or hundreds of thousands of IOPS.
- Redundancy: SAN uses zoning, multipath, redundant fabric; NAS often uses dual-controllers, network uplinks.
7. Cost & Scalability
NAS systems are generally lower cost and easier to manage, ideal for file share workloads. SAN systems require investment in switches, HBAs, zoning, and sophisticated management—but scale massively and deliver performance.
8. Real-World Decision Matrix
If workload is:
• File share, media, backups → Use NAS
• Database, large VM pool, low-latency app → Use SAN
• Mixed environment → Use both: NAS for files, SAN for high-performance block storage
9. Common Pitfalls & How to Avoid Them
- Mismatch MTU settings: Jumbo frames enabled on iSCSI but not everywhere—Leads to latency issues. Solution: Audit network end-to-end.
- Single path: A SAN host connected via one path only loses redundancy. Solution: Enable MPIO or FC dual fabric.
- Using NAS for high-IOPS VM datastore: Can cause contention. Solution: Use SAN or dedicated high-end NAS with SSD caching.
- Ignoring backup/replication: Storage is not just capacity—plan snapshot & DR early.
10. How to Get Hands-On in a Lab
- Spin a VM with TrueNAS or OpenMediaVault → create a SMB/NFS share → mount from Windows/Linux.
- Spin up an iSCSI target server (FreeNAS/Windows iSCSI) → present LUN → connect from host → format and test IOPS.
- Create a small VM cluster (e.g., VMware or Hyper-V) → use SAN storage as datastore → monitor latency, throughput.
Summary Table
| Feature | NAS | SAN |
|---|---|---|
| Type | File-level (SMB/NFS) | Block-level (iSCSI/FC) |
| Use Case | Shared files, backups | VM datastores, databases |
| Performance | Good for moderate IOPS | Designed for high IOPS/low latency |
| Complexity | Lower | Higher (fabric, zoning) |
| Cost | Lower | Higher |
Final Thoughts
In many enterprise environments you’ll find both NAS & SAN working side by side. The key is understanding which fits which workload—and avoiding using the “cheap” one just everywhere. When you match correctly, you’ll build storage infrastructure that’s reliable, performative and cost-effective.