SAN vs. NAS: Point/Counterpoint

SAN vs. NAS: Point/Counterpoint

Essential Factors For Your Workflow Storage.

Are you wondering, “Would this media production workflow be better supported with a storage area network (SAN storage) or an Ethernet network (NAS storage)?” Perhaps you are a long-time media engineer or facility manager and are considering 10 gigabit Ethernet now that it is widely available. Perhaps you are an IT manager, and this is new territory for you. Whatever your perspective, the topology issues can appear complex, and the trade-offs are not black and white.

At NetApp, we deploy petabytes of both SAN and NAS storage into media workflows. While either will work in most situations, there is usually one route that is more efficient and appropriate for a given installation. You can spend a lot of incremental money and additional deployment time if you choose the wrong protocol for the problem, so we’ve devised a rather straightforward decision tree to help organizations choose the best infrastructure.

First, hone in on the problem.

Divide the possible solutions into three categories: use cases that definitely can be addressed by NAS, those that definitely require SAN, and those that could be addressed by either SAN or NAS. Simply put, the criteria for each possibility look like this:

1. Definitely SAN — Maximum required bandwidth to individual production clients exceeds 640 megabits per second (Mb/s). For example, ProRes220 multistream editing or any uncompressed HD, 2K, or 4K editing.

2. Definitely NAS — Maximum required bandwidth to individual production clients does not exceed 300 Mb/s, or there are more than 30 clients in the workflow; required capacity exceeds 100 terabytes for every 500 megabytes per second of required aggregate bandwidth; or integration to larger corporate or enterprise IT is desirable. For example, broadcast news and sports highlights edited in a compressed video format such as XDCAM 35 or XDCAM 50 fit well into this category.

3. Could be SAN or NAS — This includes everything in between.

Then consider these issues:

1. Application performance

  • a. Smooth edit timeline playback
  • b. Network protocol overhead and switch expense
  • 2. Client connectivity expense and integration effort
  • a. Bandwidth
  • b. Maximum bandwidth required to each edit workstation
  • c. Total aggregate bandwidth needs across the workflow
  • d. Storage bandwidth as a function of cost

Application performance matters; production applications in which editors must be able to see smooth video playback do much better with a deterministic SAN protocol. So while NAS might look like it has the bandwidth for such an application on paper, the proof is in whether the editors are happy with the video playback.

Another major consideration in deciding between SAN and NAS is the cost and effort of completing the network infrastructure, including switches, cables, and client connectivity (small form-factor pluggable transceivers and host bus adapters). This topic could be its own article, but in our experience, it boils down to this: gigabit Ethernet is the least expensive and simplest; eight- and then 16-gigabit Fibre Channel are the next least expensive; and 10-gigabit Ethernet is the most expensive and complex. In fact, for media production workgroups, 10-gigabit Ethernet is not a good option. It provides no bandwidth differentiation over Fibre Channel, and it is more costly and cumbersome to deploy.

When considering bandwidth requirements, think about whether gigabit Ethernet can address the maximum client bandwidth necessary. What gigabit Ethernet can provide varies from vendor to vendor, but if you simply look at the wire speed of gigabit Ethernet (roughly 800 Mb/s), and then derate it by 20 percent (to 640 Mb/s) to ensure smooth video playback, then you’ll find a hard barrier that’s difficult to cross. That barrier makes SAN a better choice in those situations.

Finally, ask these questions:

1. What is the maximum video bandwidth that an individual production workstation is going to need?

2. How many clients will be reading and writing to the storage?

3. Is your overall workgroup bandwidth-intensive or capacity-intensive?

Jason Danielson leads media and entertainment solutions, product and solution marketing at NetApp (