Do I Need a SAN?

One of the questions that sometimes comes up when I’m consulting with business owners and IT executives is this question.  Do I need a SAN?  The answer really depends on your specific business use case and the type of data you’re storing and handling.

What is your use case?

The first thing to determine to better understand your storage needs, is what you’re going to be using the storage for.  You’ll also want to know how much date you have, and how it’s being used.  Different types of storage use cases require different solutions.  Basic file sharing is very different than a high end transaction database.

Different use cases call for different solutions.  If you have a large quantity of data, but simple performance needs a NAS (Network Attached Storage Device) might work just fine.  If on top of a lot of data you have performance needs for database or other applications that require IO a SAN might be a better fit.

Here’s a handy guide I found on

An excerpt from that article.

NAS and SAN Use Cases

NAS and SAN serve different needs and use cases. Understand what you need and where you need it.

NAS: When you need to consolidate, centralize, and share.

· File storage and sharing. This is NAS major use case in mid-sized, SMB, and enterprise remote offices. A single NAS device allows IT to consolidate multiple file servers for simplicity, ease of management, and space and energy savings.

· Active archives. Long-term archives are best stored on less expensive storage like tape or cloud-based cold storage. NAS is a good choice for searchable and accessible active archives, and high capacity NAS can replace large tape libraries for archives.

· Big data. Businesses have several choices for big data: scale-out NAS, distributed JBOD nodes, all-flash arrays, and object-based storage. Scale-out NAS is good for processing large files, ETL (extract, transform, load), intelligent data services like automated tiering, and analytics. NAS is also a good choice for large unstructured data such as video surveillance and streaming, and post-production storage.

· Virtualization. Not everyone is sold on using NAS for virtualization networks, but the usage case is growing and VMware and Hyper-V both support their datastores on NAS. This is a popular choice for new or small virtualization environments when the business does not already own a SAN.

· Virtual desktop interface (VDI). Mid-range and high-end NAS systems offer native data management features that support VDI such as fast desktop cloning and data deduplication.

SAN: When you need to accelerate, scale, and protect.

·  Databases and ecommerce websites. General file serving or NAS will do for smaller databases, but high-speed transactional environments need the SAN’s high I/O processing speeds and very low latency. This makes SANs a good fit for enterprise databases and high traffic ecommerce websites.

·  Fast backup. Server operating systems view the SAN as attached storage, which enables fast backup to the SAN. Backup traffic does not travel over the LAN since the server is backing up directly to the SAN. This makes for faster backup without increasing the load on the Ethernet network.

·  Virtualization. NAS supports virtualized environments, but SANs are better suited to large-scale and/or high-performance deployments. The storage area network quickly transfers multiple I/O streams between VMs and the virtualization host, and high scalability enables dynamic processing.

Additional Items to Consider

There are a few more items I would consider as well.  The first of which is whether you plan to use High Availability in this environment.

HA refers to a setup where the SAN is the main storage unit and there are multiple VMware hosts that all connect to that SAN.  The servers are set up in such a way that if any one host were to fail there is an automatic fail-over of those VMs to the other servers.  This is only possible with a shared storage model, and can require additional licensing for both VMware and your SAN.

The resulting solution however, is extremely robust.  This type of architecture allows you to have much higher uptime, and is perfect for workloads that can’t ever be down.  HA is one of the key features that a SAN offers, and is an important consideration when choosing a storage solution.  The cost can be significant to small businesses, so that is always part of the decision.

Data transfer rates are another item to consider.  If you have TB of data that change significantly backing them up can become a challenge.  SANS usually have either a fiber channel or 10GB network card that allows for faster data transfer assuming you couple them with 10GB networking.

NAS can also come with 10GB network interface as well, but it’s much more common for them to come with a GB NIC.  This is another factor to consider when examining your storage needs.  In addition to the storage itself, you may need to upgrade some of your core network switching to get the full performance out of your storage.


Take a good look at the use case.  NAS are great for centralizing and sharing data.  SANS are great for accelerating, protecting and scaling your data.  There are definitely a lot of things to consider with a project of this magnitude.  If you’re stuck or want some assistance know that i.t.NOW is here to help.  We have some great systems architects that can help examine your specific use case and make a recommendation that will be a perfect fit for your business.