How do SAN and NAS storage differ?
SAN storage and NAS are two different types of data storage. A NAS provides file-level access to data, while a SAN provides block-level access, the kind needed to load an operating system, for example.
| SAN | NAS | |
|---|---|---|
| Access | Block level | File level |
| Protocols | Fibre Channel or iSCSI | SMB (CIFS) and NFS |
| Network | A dedicated storage area network, typically with redundant Fibre Channel switches | Your existing Ethernet network, normally one or two switches |
| Operating system | Embedded, for storage management only | Typically Linux, integrating with LDAP or Active Directory |
| Performance | Generally faster, with lower protocol overhead | Generally slower than a SAN |
| Typical use | Databases, transactional applications, virtualisation, backup appliances | Shared files and folders for users |
SAN Storage – Storage Area Network
SAN storage is a block-level storage protocol. Block storage uses a protocol like Fibre Channel or iSCSI to create a direct connection between servers and storage devices. This architecture allows high performance, making it ideal for databases and transactional applications.
Blocks are presented to the application or operating system as LUNs (logical unit numbers). The SAN provides these and they connect to the server via an HBA (host bus adapter). The data blocks appear as locally attached storage (DAS), even though the storage resides on the SAN. A SAN should always run on a dedicated Storage Area Network.
Scalability is another key factor. As your organisation grows, a SAN can be expanded with little disruption, so you can adapt to changing storage needs.
Trends such as software-defined storage and cloud integration are changing how organisations scale their infrastructure and manage costs, and some vendors now add AI-based monitoring to SAN management.
A SAN usually needs more up-front investment than a NAS, so weigh the whole-life cost against what your workloads actually need.
NAS Storage - Network Attached Storage
NAS storage provides a centralised file sharing area for storing files. The NAS has an operating system, typically Linux, and this integrates directly with LDAP or Active Directory so that designated users can store and access files across the Ethernet network.
File-level access refers to the way data is stored and retrieved in a network attached storage (NAS) environment. Unlike block storage, which deals with data as blocks, file-level access manages information in discrete files, so users can interact with data at a more granular level.
When you save or retrieve a file on NAS storage, you are accessing it directly rather than dealing with chunks of raw data. This makes operations simpler and more intuitive for users who are used to working with files and folders.
File-level access also supports protocols like SMB (Server Message Block) and NFS (Network File System), allowing compatibility across different platforms. That flexibility helps collaboration between teams using diverse operating systems.
SAN and NAS connectivity
SAN storage connectivity
Connecting SAN storage to your storage area network will use one or more of the following:
- 8/16/32/64/128Gb/s Fibre Channel = FC SAN
- 1/10/25/40/100Gb/s Ethernet = iSCSI SAN
NAS storage connectivity
Connecting NAS storage to the network normally uses Ethernet:
- 1/10/25/40/100Gb/s Ethernet
A SAN normally has multiple redundant Fibre Channel switches connected to redundant storage arrays. The storage is carved up and served out as data volumes. These volumes can provide storage for virtualisation, local disk storage to servers attached to the SAN, or disk storage to backup appliances where block storage is a key requirement.
A NAS normally connects to one or two network switches. Its storage is carved up into volumes, which are then used to provide files and folders accessed across the network as CIFS/SMB or NFS shares that users map to their desktops.
SAN storage vs NAS Performance
SAN storage is typically faster than NAS because the Fibre Channel and iSCSI protocols have lower processing overhead, enabling data to be sent across the SAN at close to wire speed. Both systems can use HDD, NVMe and SSD drives internally, but performance will generally be greater across a SAN.
How do NAS storage and SAN storage differ?
A NAS has an operating system, CPU, memory, data storage and network connections. A SAN has a CPU, memory, data storage, network connections and an embedded operating system for storage management. A SAN will not let you add extra functionality, such as a photo-sharing app. Because that embedded operating system is not designed to be changed or modified, a SAN is generally considered the more locked-down option.
By default, a LUN is presented to the connected server rather than shared. Software is available to share LUNs between multiple hosts, which is commonly used in post-production to share large files across the network while locking them when they are being accessed.
A NAS, on the other hand, by default shares all the available volumes across the network to any user who has file or folder permissions.
Which should I choose?
Ultimately it boils down to your budget and requirements. In the end it is horses for courses: NAS for file and SAN for block.
Choose a SAN if you need…
- Block storage for databases, virtualisation or backup appliances.
- The highest performance and a locked-down infrastructure.
- A dedicated storage network. iSCSI will run over an existing Ethernet network, but a dedicated one is recommended.
Choose a NAS if you need…
- Shared files and folders for users and teams.
- Something that sits happily on your existing network.
- Access across different platforms through SMB and NFS.
Unsure what is best for you, or how to implement it?
Give us a call. We help customers from primary schools to multibillion-pound organisations achieve their IT strategies, and we take an individual approach to every project.
Smarter, strategic thinking for your storage
Tell us what you run today, what you need to store and how fast it is growing. We will talk you through whether a SAN, a NAS or a mix of both fits your IT strategy.
Prefer email? Write to solutions@data-storage.uk.
