Storage Networking 101
BackBy Shawn Conaway — March 2009
Storage networking traditionally has been based on fibre channel, an out-of-band solution that isolates storage traffic to the storage environment. The benefit is that there is no contention for network resources. You don’t have to worry about some clown bringing down your network by streaming the “Lord of the Rings” movie trilogy over his lunch break since the network is isolated and dedicated only to storage.
Further, this isolation make the storage network generally more secure than Ethernet, and fibre-connected devices generally are more reliable since all the connections are fully redundant. Any component along the fibre channel path can fail and the system will still remain running.
The impetus for accessing storage via Ethernet is a fairly recent phenomenon. Support for iSCSI Storage, say on a LeftHand SAN (storage area network), supported by VMware for a few years. Accessing NAS (network-attached storage) via NFS (network file system) or CIFS (Common Internet File System) has had traction for a bit longer, but it has only been during the past few years that people seriously considered using these protocols for mission-critical systems. When it comes to Ethernet networking, the name to know is Cisco. has only been
One major drawback with using Ethernet to access storage is that storage I/O will compete with regular network traffic. A mass e-mail or a virus outbreak can eat up network bandwidth, potentially causing disk corruption if a given system cannot write to disk.
However, if you work for a small company, a big load on your Ethernet network may not be a big deal if there isn’t much traffic on your LAN. More importantly, you may be willing to live with the performance issues caused by bursting network traffic if you don’t have the money to buy a separate fibre or Ethernet network. Fibre switches still cost tens of thousands of dollars.
There is an industry trend toward using a single converged network card (CNA) instead of separate HBAs (host bus adapter) and NIC (network interface controller) cards. The CNA cards support both fibre and Ethernet protocols at 10 Gbps. This convergence will enable a single adapter to provide fibre over Ethernet (FCoE).
Learning the Ropes
Let’s look at Cisco first. Cisco offers a training plan for the Cisco Data Center Storage Networking Design Specialist. Some great resources to study for the certification are Cisco’s Storage Networking Fundamentals and Storage Networking Protocol Fundamentals.
Cisco also has a more general Cisco Certified Entry Networking Technician. References for the CCENT include Cisco’s CCENT Official Exam Certification Guide or Que’s CCENT Exam Cram and Exam Prep guides. (CCENT) certification.
Shawn Conaway, VCP, MCSE, CCA, is a director of NaSPA and editor of Virtualize! and Tech Toys magazines. He can be reached at firstname.lastname@example.org.