SAN or NAS: Which Way to Go?By David Strom | Posted 2008-02-21 Print
Video puts pressure on enterprise IT infrastructures. Here’s how to keep up with storage and availability demands.
SAN or NAS: Which Way to Go?
Adding video capabilities to a network nearly always requires adding storage. Even the lowest-resolution video files eat up several hundred megabytes; just a few videos can sap your existing storage capacity quickly.
Enterprises have two options: a storage-area network (SAN) or network-attached storage (NAS). Different uses will motivate different kinds of purchases. If performance is more important than capacity, go with a SAN because it can access data faster than direct storage access and is often easier to expand and manage. But choose a SAN solution designed specifically for video. It may cost more, but the low latency is a must for work with video files.
If you’re seeking a more cost-effective approach, NAS is the answer, especially if you only need to host a limited amount of low-bandwidth content on your network. NAS allows you to share a file with hundreds of clients without designing any complex clustering solutions or making any changes to client software. And a NAS system that can grow into a SAN may make sense if you expect to add a lot of video down the road.
For example, a major Washington trade association is replacing a 4-year-old SAN with a new Network Appliance NAS FAS2020. “Hopefully, this purchase will get us through the next five years with much simpler maintenance than the complex system it’s replacing,” says Adam Kuhn, IT manager for the association. “The SAN was just being used to serve files and didn’t have multiple servers or fibre attachments. It was just a big drive in the sky.”
Kuhn likes the fact that he can triple existing storage capacity and simplify support needs: The FAS2020 can notify Network Appliance when a failure is about to occur. “They can dispatch a replacement part automatically—what could be better than that?” he says. “And there is no Windows Server operating system to maintain, either.”
The organization’s older SAN used SCSI drives, while the new NAS uses SATA drives, which are less costly per gigabyte of storage, Kuhn says.
No matter which method you choose, video storage is likely to grow quickly, because the files are so large compared with most spreadsheets and other documents. To manage this, enterprises might consider a chargeback scheme for the additional storage capacity. “If [users] have to pay for extra storage, they will take the time to consider what files are really pertinent that they need to keep,” says Green at Brooks Health. “Data belongs to the individual business unit, not the IT department, and putting a price tag on it helps to instill some level of ownership.”
Upgrading Network Infrastructure
Simply upgrading storage isn’t always enough. You need to understand the limitations of your operating system to handle very large files and the existing network traffic patterns to determine whether you’ll have sufficient bandwidth to handle video.
While ordinary 10 MB or 100 MB Ethernet will get you limited resolution for a reasonable number of video streams, many corporations are upgrading to 10 GB networks for their heaviest video users, and some are replacing all their network connections everywhere.
“Video definitely stresses your network—you run into latency issues, packet-loss issues,” says Burzin Engineer, vice president of technology for Shopzilla, an Internet-based comparison-shopping service. “Having a 10 GB Ethernet network definitely helps, especially if you have upgraded within the past couple of years.”
Performance can also suffer when video traverses wide-area networks or goes across the public Internet, where there is little control over latency.
In some cases, corporations moving to voice over IP (VoIP) are also considering the latency requirements for handling video when they make these network upgrades. Brooks Health, for example, is installing all new network infrastructure along with its new SAN and is considering multiprotocol label switching (MPLS) to accommodate video and VoIP and provide redundancy.
Many experts suggest employing specialized content delivery network providers such as Akamai for handling the Internet portion of their content distribution. These service providers “have spent millions of dollars to build a network that has the kind of scale and performance you need for these types of applications,” Engineer says.
Another option: Invest in a better storage network and upgrade your Ethernet connectivity for all users.
The Big Picture, in Technicolor
Video also brings infrastructure management challenges for enterprises. And the tradeoffs between better SAN or NAS devices and better network throughput can be vexing, depending on the vintage of the existing storage servers and network gear, and the types of video users consume.
“You want to make sure the experience of the first users is positive,” says Dan Kusnetzky, an analyst with Kusnetzky Group in Osprey, Fla. Indeed, first impressions count, especially when it comes to video.
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