SAN VS. NAS: A Comparison

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Storing data in a safe, secure, and reliable manner has always been a significant concern for those working within a distributed networked environment. In this article, we will be exploring two specific methods of managing, preserving, and archiving information. These methods include using the SAN or Storage Area Network or the NAS or Network Attached Storage protocols. Both protocols provide a networked storage solution, but the main difference is in the approach and implementation. A NAS device is usually a single storage unit, while a SAN is typically a network cluster of several devices. Sometimes both these methods are employed and combined into a single medium called a Unified SAN

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Definitions

What is a SAN?

A SAN is a cluster of networked storage devices. It uses a block-level design storage method to share pooled resources. This enables the attached devices to use blocks to access and store data. The data blocks are stored by LUN’s or Logical Unit Numbers. These LUNs are submitted to the server from the storage medium. When a server looks at these LUNs, they appear the same as a local drive (or DAS – Direct Attached Storage). If you store data with the SAN protocol, it may require specialized hardware to transfer trafficked data over a network. These hardware types can include Fibre Channel, iSCSI, or FCoE. SAN hardware is divided up into three defined components:

  • The Host Layer: The servers accessing the SAN.
  • The Fabric Layer: Controls the networked devices.
  • The Storage Layer: Implements the hardware devices.

A SAN offers fast, resilient storage and, as such, is frequently the storage protocol of choice for high-performance applications or databases.

What is NAS?

A NAS is usually a dedicated hardware device that runs a preinstalled OS connected to a local area network via an Ethernet connection. Instead of using block storage like a SAN, the data in a NAS uses volumes comprised of files and folders. Users access these files and folders across a network, which the NAS device shares. Since a NAS device is independent of the connected devices, multiple users can simultaneously connect to the NAS. 

What is Unified Storage?

Unified storage (or multi-protocol storage) combines both file and block storage capabilities into a single storage system. These combined systems support multiple protocols. These controllers allocate storage for the physical processing for the NAS or SAN.

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Benefits

Benefits of SAN

  • Performance – The overall speed of a SAN is significantly higher than a NAS as there is little issue with network bottlenecks. 
  • Volume Size – A SAN can be easily increased to a virtually unlimited size.
  • Backup Speed – Since an OS views the SAN as attached storage, backup speeds are increased, making for faster backups without escalating the load network.
  • Scalability – The ability to scale a SAN has no specific limitations as to capacity. The only restriction being cost.
  • Redundancy – Because SANs live at a different layer of abstraction, it allows for the addition of multiple devices within the cluster, increasing stability.
  • Disaster Recovery – The need for seamless business processes drives many corporations to use a SAN-based architecture to ensure the continuity of operations.

Benefits of NAS

  • Architecture – NAS data lives in volumes of files and folders instead of blocks in a typical client-server based architecture.
  • Security – NAS provides security via user access controls and redundant data structures. 
  • Efficient – NAS allows for an easy, quick, and low-cost method for data storage.
  • Inexpensive – NAS is less expensive to purchase and maintain, although the cost of a high-end NAS will cost more than an entry-level SAN. 
  • Stability – Utilizing NAS removes individual servers as single points of failure.
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Drawbacks

Drawbacks of SAN

  • Complexity – A SAN can add additional layers of complexity to existing systems, increasing workload management.
  • Cost – Implementing and managing a SAN can be cost-prohibitive for first-time users.
  • Management – A SAN may be challenging to manage and may require a dedicated specialist to administrate it.

Drawbacks of NAS

  • Single point of failure – Because NAS is considered a “local” on-site backup drive, failures can occur, leading to data loss. 
  • Speed – Heavy use of a NAS system can cause significant network congestion and lower transfer speed. 
  • Scalability – NAS devices are not easily scalable due to the limitations of the hardware.
  • Quotas – System admins must enforce user quotas to prevent over utilization of shared space.
  • Management – Basic networking knowledge is required to implement a NAS.
  • Functionality – Capabilities will vary depending on manufacturer, chip, and size. Typically, only used for storage. 

Comparison

SANNAS
Block-level accessFile-level access
Higher performance due to the infrastructureHigh performance using network/software optimization, usually slower
Needs CustomizationEasy to configure
Needs network configurationsEasily networkable
Requires separate servers for apps or user access levelsIndependent device
Suitable for mission-critical appsSuitable for latency-tolerant apps
Grants read/write access for multiple users using external managerGrants read and write access for multiple users by default
Increased costs – infrastructure expensesLower cost, simple to deployment
ScalableDurable
Effective for big data or performance-crucial businessCan be handy for a business of any size
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NAS or SAN: Which Platform is Better for You?

Typically, SMBs would be better served utilizing a NAS device, whereas larger entities with the resources to invest in the architecture and management would profit from employing a SAN. Below is a checklist of considerations to discuss when reviewing the need for storage options.

  • Architecture Needs
  • Data Processing Models
  • Network Protocols and Capabilities
  • Performance Constraints
  • Scalability Requirements
  • Management Assets
  • Backup Challenges
  • Redundancy Imperatives
  • Disaster Recovery Dictates
  • Virtualization Options
  • Price (TCO)

Evaluating these parameters prior to investing in a storage system will provide a clearer picture when defining the needs of an organization. Liquid Web has multiple storage options available to meet any storage need and can be discussed and evaluated with one of our experienced Solutions Providers.

Conclusion

To a connected OS, a SAN usually appears like a local disk drive but exists as a network of separate storage devices, while a NAS looks like a simple file server. Overall, NAS is inexpensive, reliable, and ideal for SMBs looking to implement a simple storage solution. SANs are more complex, high-performing, and suitable for mission-critical apps. Companies looking for top-of-the-line storage, performance, and reliability would be best served using a SAN.

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Author Bio

About the Author: David Singer

I am a g33k, Linux blogger, developer, student and Tech Writer for Liquidweb.com/kb. My passion for all things tech drives my hunt for all the coolz. I often need a vacation after I get back from vacation....

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