There are two standard types of network storage, called Network Attached Storage (NAS) and Storage Area Network (SAN). The terms NAS and SAN are often confused with one another because the acronyms are similar.
Network Attached Storage (NAS)
NAS is a kind of storage device that provides local area network (LAN) nodes with file-based shared storage through a standard Ethernet connection. A NAS server typically contains multiple hard drives, providing a large amount of centralized storage space for connected computers to save data. Instead of each computer sharing its own files, the shared data is stored on a single NAS server. This offers an easy way for multiple users to access the same data, which is important in situations where users are collaborating on projects or utilizing the same company standards.
Because of their centralized nature, NAS servers are often used in business networks and become more common in home networks nowadays. They are mainly used for:
- File sharing
- Data backup/disaster recovery
- Network printing
- Multimedia file sharing
- Media server
Advantages of NAS
- Convenient: it provides consolidate space of storage within the network. That means it is easier to collaborate on the server and to the machine.
- Reliable: most NAS supports RAID 0, RAID 1 and RAID 5, which makes your data safer. When the data stored on one drive has been destroyed, it can be recovered from another drive.
- Affordable: NAS devices cost less than normal servers and have low energy consumption.
- Easy: Fast and easy installation/configuration and administration.
Disadvantages of NAS
- Network dependent: Since files are typically shared with NAS devices over the LAN (local area network, also used for normal traffic), they can cause congestion or can be affected by other traffic on the LAN. Therefore, NAS is not suitable for data transfer intensive applications.
- Minimal speed: With low throughput and high latency, a NAS is not fast enough for high performance applications e.g. big database.
Storage Area Network (SAN)
SAN is a dedicated high-speed network or subnetwork that interconnects and presents shared pools of storage devices to multiple servers. Each server on the network can access hard drives in the SAN as if they were local disks directly attached to the server. When a host wants to access a storage device on the SAN, it sends out a block-based access request for the storage device.
SAN combines the flexibility and sharing capabilities of NAS with the much of the performance of Direct Attached Storage (DAS). However, it is far more complex and costly than NAS. A SAN consists of dedicated cabling e.g. Fiber Channel (FC) or Ethernet based iSCSI, dedicated switches and storage hardware. It performs best when used with Fiber Channel medium (optical fibers and a fiber channel switch) but it is very expensive, complex and difficult to manage. Ethernet-based iSCSI has reduced these challenges by encapsulating SCSI commands into IP packets that do not require an FC connection. It is particularly useful for small and midsize businesses that may not have the funds or expertise to support a Fiber Channel SAN.
As SAN is a block level storage solution, it is best suited for high performance applications such as:
- Databases (MS SQL, MySQL, PostgreSQL, etc.)
- Media Libraries
- Backup Archives
- High Usage File Servers
- E-mail Servers
- Remote vaulting and mirroring
- Heterogeneous platform support
- Storage-level replication
- Storage-level backups
Advantages of SAN
- Better disk utilization: Rather than having several servers with various levels of hard drive utilization, a SAN allows you to pool your storage and dynamically allocate exactly what each server requires.
- Higher performance: SAN performance is not affected by Ethernet traffic or local disk throughput bottlenecks. Data transmitted to and from a SAN is on its own private network partitioned off from user traffic, backup traffic and other SAN traffic.
- Better availability for applications: Storage is externalized, independent of the application, and accessible through alternate data paths such as found in clustered systems.
- Effective disaster recovery: SAN spans over a distant location containing a secondary storage array. This enables storage replication either implemented by disk array controllers, server software, specialized SAN devices.
- Dynamic failover protection: Provides continuous network operation, even if a server fails or goes offline for maintenance, which enables built-in redundancy and automatic traffic rerouting.
- Highly scalable: Servers and storage devices may be added independently of one another, and do not depend on proprietary systems.
Disadvantages of SAN
- High complexity: It is a network of intricate and interconnected devices and implementation entails major device and architectural changes. Building and managing a SAN requires a specialized skill set.
- Upfront cost: SAN hardware tends to be expensive. Although it brings instant ROI by addressing the problems of storing, managing, and protecting data in a growing environment, the upfront costs of hardware and network implementation can be a major deterrence.