This article will introduce and compare Network Attached Storage (NAS) and Storage Area Network (SAN) solutions. The goal is to understand the key differences between these two common networked storage technologies.
Definition of NAS
NAS stands for Network Attached Storage. It is a storage device that is connected to a network and allows authorized users to access and store data from a centralized location (Seagate, 2022). NAS systems consist of one or more hard drives contained in a single enclosure that is directly attached to a local area network, rather than through a server computer. The NAS enclosure has its own network address, rather than being dependent on a server computer’s IP address. NAS provides file-based shared storage independent from a file server (TechTarget, 2022).
Some key characteristics of NAS include:
- Provides centralized storage accessible over a network
- Contains hard drives in an enclosure with network connectivity
- Does not require a dedicated file server computer
- Operates as an independent network device with its own IP address
- Supports file-level storage and retrieval
Definition of SAN
SAN stands for Storage Area Network. A SAN is a dedicated high-speed network that provides access to block-level storage devices like disk arrays and tape libraries (HPE, 2022). SANs connect servers to storage devices using technologies like Fibre Channel, iSCSI, Infiniband or Fiber Channel over Ethernet.
SANs provide block-level access to storage, meaning the SAN provides servers with access to raw block storage devices. This allows multiple servers to access storage devices directly and independently of each other. The main advantage of a SAN is it allows shared storage between servers so any server can access any storage device (TechTarget, 2022).
Architecture
NAS and SAN have fundamentally different architectures.
SAN is typically implemented as a dedicated storage network separate from the local area network (LAN). It uses block-level storage protocols like Fibre Channel, iSCSI, or Fibre Channel over Ethernet (FCoE). SAN provides block-level access to storage. The storage appears to SAN clients as locally attached drives. This allows faster access since it doesn’t have to go through the network protocol stack. Storage
In contrast, NAS uses file-level storage protocols like SMB, NFS, or AFP over the TCP/IP network. NAS is directly attached to the LAN and provides shared file systems to clients. The NAS server handles file I/O requests from clients through the network file sharing protocol. This adds CPU overhead compared to SAN’s block-level access. Mecba
In summary, SAN provides block storage over a dedicated network, while NAS provides file storage over the LAN. SAN appears as local disk to clients while NAS exports file systems over the network.
Scalability
NAS systems are usually limited in how much they can scale, both in terms of storage capacity and performance. Most NAS appliances max out at around 100 TB, though some enterprise NAS can scale up to multiple petabytes. But at a certain point, NAS architectures start to run into I/O bottlenecks that limit performance as more drives are added. SANs are designed for high scalability from the start. A well-designed SAN can easily scale to multiple petabytes of capacity while maintaining high throughput and IOPS with the right network architecture. The centralized architecture of SANs also makes it easier to add capacity in large chunks. Overall, SANs are much more scalable than NAS in large environments that require expansion over time. As noted by Hypertec, SANs are better suited for large-scale, high-performance deployments that require heavy throughput and IOPS (https://hypertecsp.com/knowledge-base/nas-vs-san/).
Performance
When comparing the performance of NAS and SAN in terms of speed and throughput, SAN generally provides better performance. According to Whitehats, SAN is optimized for speed and allows multiple users to access data simultaneously without performance hits. In contrast, NAS can suffer performance degradation when multiple users access the same files concurrently.
SAN utilizes a dedicated storage network separate from the LAN which helps reduce bottlenecks. As noted on How2Shout, the specialized SAN network offers higher bandwidth and lower latency. SAN also uses advanced caching techniques to accelerate I/O. Meanwhile, NAS relies on standard Ethernet and is subject to congestion on the LAN.
According to discussions on DataCenterTalk, SAN supports faster disk technologies like SSD and NVMe for better performance. NAS is generally limited to HDDs and slower disk interfaces. For applications that demand high throughput like databases, SAN is usually the better choice over NAS.
Availability
When comparing availability and redundancy between NAS and SAN, there are some key differences to consider:
SANs offer higher availability and redundancy through features like redundant fabrics, controllers, RAID configurations, and hot swappable components. SAN storage networks are designed specifically for high availability with no single point of failure (Backblaze.com). SANs allow storage volumes to be shared across multiple servers, so if one server goes down the storage is still accessible. SANs also enable clustering between servers for failover protection (Hypertecsp.com).
NAS can offer redundancy through features like RAID disk configurations, but the single NAS appliance itself is a potential single point of failure. Most NAS devices have high-availability capabilities like dual network ports and redundant power supplies, but cannot match the complete redundancy of enterprise SAN architectures. However, modern NAS devices often have clustering capabilities to enable failover to another appliance (Networkworld.com).
Overall, SAN designs offer the highest levels of availability and redundancy for mission critical systems and maximum uptime requirements. NAS can approach SAN in redundancy capabilities but lacks the full redundancy of enterprise SANs across fabrics, controllers, servers, etc (Backblaze.com). But for less critical workloads, modern NAS devices have strong high availability options as well.
Security
When it comes to security, NAS and SAN differ in some key ways. NAS typically relies on host-based security measures like access control lists, user authentication through accounts, and file-level encryption. Most NAS devices allow admins to set permissions for which users or groups can access, modify or delete files on the NAS. Many also support encryption of the full storage volume or select files/folders (Source 1).
SAN storage offers more granular security controls at the block level. SAN administrators can apply permissions, encryption and access control policies to specific volumes, LUNs and blocks. SAN also permits zoning to isolate and restrict communication between certain servers and storage. So SAN generally provides stronger security isolation and access controls than NAS (Source 2). However, both NAS and SAN encryption can be circumvented if drives are physically accessed.
Overall, SAN offers more robust security options for large multi-user environments where granular control over storage access is critical. NAS security may be sufficient for smaller organizations with simpler needs.
Cost
NAS devices typically cost less than SAN solutions in terms of hardware, setup, and maintenance. According to Hypertec (https://hypertecsp.com/knowledge-base/nas-vs-san/), although high-end NAS can be more expensive than low-end SAN, NAS is generally less expensive to buy and maintain. NAS are considered appliances that connect to a network, while SAN requires its own dedicated infrastructure. Backblaze (https://www.backblaze.com/blog/whats-the-diff-nas-vs-san/) also notes NAS is less expensive compared to SAN. According to Tiger Technology (https://www.tiger-technology.com/nas-vs-san-should-it-really-all-be-about-the-lowest-cost-2/), NAS solutions are commodity storage readily available at a range of price points, while SAN requires dedicated infrastructure driving up costs.
Use Cases
NAS and SAN have different strengths that make them suitable for different use cases:
NAS ideal for:
- File storage and sharing
- Backing up desktops and laptops
- Storing media files for editing
- Applications that need fast access to files
NAS provides file-level access, making it a good choice for storing and sharing files that don’t require high performance. The simple architecture is easy to set up for backups and personal storage.
SAN ideal for:
- Database storage
- Transactional applications
- Virtual machine storage
- High performance computing
SAN provides block-level access for high performance needs. The fast interconnects and scalable architecture make SAN suitable for latency-sensitive applications that demand high throughput.