NAS vs. SAN: A Comprehensive Comparison

SAN is a dedicated network used for block-level data storage made up of an interconnected pool of storage arrays, host bus adapters, switches and servers that provide access to data to end users. A SAN can also utilize virtual storage nodes known as virtual SANs or vSANs, as well as tape libraries from servers in addition to storage arrays. The server accesses the data on the hard disk array or virtual node in the same way a computer accesses data on a local attached hard drive—in fact, when navigating to file directories with a SAN, they appear as if they’re locally attached.

SAN is typically connected by the Fibre Channel (FC) data transfer protocol but also can be connected via iSCSI (Internet Small Computer System Interface), Fibre Channel over Ethernet (FCoE) and a variety of other ways. FC allows for rapid transfer speeds that can be anywhere from 2GB/s to 128GB/s and is commonly used in business-critical enterprise applications. iSCSI and FCoE are less common block protocols that uses an Ethernet connection rather than FC and are typically used in small and medium-sized business applications due to cost.

With SAN, the data is shared amongst multiple disk arrays and there are multiple switches and servers as well. If a server, switch or disk array fails, the data is still accessible. Plus, you only need a single backup server, freeing up your other servers for other tasks.

You can continue to scale your SAN configuration without having to interrupt your network connection, provided you have the space and financial resources to do so.

SAN is not part of the local area network (LAN) and therefore isn’t subject to issues such as bottlenecking due to lack of available bandwidth, improving overall application availability and performance.

In the event of a cyberattack or unexpected disaster, businesses can be destroyed overnight. SAN makes for easy and reliable data backup and recovery since all your data is backed up continuously. The nature of the SAN being separate from your LAN isolates your sensitive data, making it secure from external threats.

With SAN, the data is shared amongst multiple disk arrays and there are multiple switches and servers as well. If a server, switch or disk array fails, the data is still accessible. Plus, you only need a single backup server, freeing up your other servers for other tasks.

You can continue to scale your SAN configuration without having to interrupt your network connection, provided you have the space and financial resources to do so.

NAS is a file-based data storage device connected to your LAN that can serve files to any network-connected device. Sometimes, NAS will have built-in software designed for serving files. Servers see NAS storage as a shared network-mounted volume, and you would need to map a file location to access it. Data transfer speeds for NAS devices typically fall in the 3 – 20MB/s range for consumer-level devices and up to about 110MB/s for high-end, modern NAS devices.

A NAS typically has multiple hard drives in a RAID (Random Array of Independent Disks) configuration for the sake of storage efficiency and/or data redundancy in the event of a hard drive failure. The exact functionality depends on what RAID configuration you choose (RAID 0, 1, 5 and 6 being the most common). A NAS device will have a network interface card (NIC), allowing it to connect to a switch, router or gateway for network access.

A NAS device is usually attached to a TCP/IP network (usually Ethernet) using NFS, CIFS or HTTP that serves up files to users within the LAN. Since the NAS is LAN-dependent, so if you have a network outage your data is inaccessible. Additionally, the file transfer speed will also be dependent on your network bandwidth and the NAS hardware itself. A NAS is a file system, unlike SAN, which is broken up into blocks consisting of smaller blocks and bits, lending to its greater performance.

Relative to SAN, a NAS device is relatively inexpensive. The only additional costs you’ll have are additional hard drives if you choose to expand your NAS storage (if your NAS has more hard drive bays, that is).

Using a NAS isn’t too much different than how you access Dropbox or Google Drive files: a NAS is essentially your own private cloud storage and server. It’s very easy for the average user to get up and running with a NAS device.

There’s no third parties involved with your NAS, you don’t have to worry about data breaches or unauthorized users digging through your files, provided your security protocols are up-to-date.

You can use RAID to duplicate your data in the event one of your hard drives fail. Some NAS devices will have helpful software that will warn you if it detects one of your hard drives is about to fail.

If something happens to go awry with the NAS, no devices will be able to access the files on the NAS.

Your ability to scale the storage of a NAS is limited to the number of drive bays your NAS has. It is possible to scale-out multiple NAS devices but this does require a fair amount of technical expertise.

Data transfer with a NAS is much slower than with a SAN. It’s also slower than direct attached storage (DAS). Note: you can also use a NAS device as DAS by simply plugging it directly into your computer.

Enterprise/large businesses typically have SAN since it’s much faster, more scalable and available for all business-critical applications than NAS. For instance, Oracle and Microsoft SQL database, which are I/O-intensive applications, require the performance only SAN can provide. Many enterprise-level companies use a combination of SAN and NAS.

• Home- if you want to share files more easily with people within your home while automatically backing up your files and don’t want to pay for cloud storage options like Dropbox/Google Drive/OneDrive, a NAS device is a great purchase. If you drop your external hard drive, your data may be done for. With a NAS, you have data redundancy, so all your valuable files are protected.
  
  Small/Medium Businesses- NAS performance exceeds that of remote cloud servers, provided you have a fast LAN connection and a modern NAS device. Accessing remote cloud servers depends on having an internet connection and how quick the servers are in doling out the files. Some NAS models can exceed a maximum single volume size of 200TB, which should be more than enough for most small businesses.

We hope this guide has been helpful in guiding your decision-making process. CDW helps businesses, from startups to enterprise, achieve their IT goals. We partner with the top tech OEMs that sell both NAS and SAN solutions. Learn more about our data storage and backup solutions and be sure to contact CDW if you need a consultation.