Fibre Channel (FC) has been a staple in storage area networks (SANs) for years, offering reliable and secure data transfer between storage resources. As organizations explore new storage network options, such as NVMe over Fabrics (NVMe-oF), it’s crucial to have a solid understanding of FC fundamentals.
By mastering FC fundamentals and staying current with the latest developments, you’ll be well-equipped to make informed decisions about your organization’s storage network strategy and unlock the full potential of your storage resources.
Table of Contents
Question 1
Pick the statement that correctly describes FC.
A. It was developed for connecting servers to shared storage devices in a SAN.
B. It runs only on optical fiber.
C. It supports block, file and object storage.
D. It works between devices that are no more than 1 km apart.
Answer
A. It was developed for connecting servers to shared storage devices in a SAN.
Explanation
Unlike other storage networking technologies, FC was developed specifically to connect servers with shared storage devices in a SAN. The Fibre Channel basics you should know include that it’s only used for block storage. It delivers raw data blocks between devices as far as 10 km apart if they’re connected by optical fiber. When it was first developed, FC ran only on optical fiber, but now it also runs on coaxial cable and twisted pair lines.
Question 2
Which isn’t a characteristic of Gen 6 FC?
A. 32 Gbps speeds
B. A parallel configuration in which four lanes can be aggregated to achieve 128 Gbps throughput
C. More flexible than Ethernet
D. Improved power efficiency as measured in throughput per watt
Answer
C. More flexible than Ethernet
Explanation
With the advent of Gen 6 FC, network throughput doubled to 32 Gbps from Gen 5’s 16 Gbps, speeding application response and eliminating I/O bottlenecks. Gen 6’s parallel linking capability enables four data lanes that can be combined into a single 128 Gbps link. Gen 6 also has features that lower energy consumption, according to the Fibre Channel Industry Association. However, Ethernet is generally considered more flexible than FC, particularly because it’s able to more readily adapt to new technologies and environments.
Question 3
Which statement is a downside of FC?
A. It’s unreliable.
B. It can be difficult to manage.
C. It can’t be used for arbitrated loops.
D. It doesn’t have a high degree of security.
Answer
B. It can be difficult to manage.
Explanation
FC has long been considered the better performing and more reliable storage networking technology by many in the industry. It’s used for point-to-point connections, as well as arbitrated loops or rings, and it has a high degree of security. However, FC technology is considered expensive and difficult to manage.
Question 4
What’s driving the switch to 32 Gbps FC?
A. Bandwidth-related latency issues when flash is used with 8 and 16 Gbps FC
B. Bottlenecks in storage devices as more flash is used
C. Significantly lower costs
D. All of the above
Answer
A. Bandwidth-related latency issues when flash is used with 8 and 16 Gbps FC
Explanation
Bandwidth-related latency can become an issue in an 8 or 16 Gbps FC network as an enterprise deploys more and larger workloads. This is most likely to happen if the enterprise is using flash media. Moving to 32 Gbps FC can alleviate this sort of congestion. As flash is more frequently used, bottlenecks are more likely to appear in the network rather than in storage devices. FC is also still relatively expensive, so cost is unlikely to be a driving factor in the switch to 32 Gbps FC.
Question 5
Which of the following is true about NVMe over FC?
A. Any 16 Gbps or 32 Gbps FC host bus adapter (HBA) or switch will support NVME over FC, while also providing SCSI over FC services.
B. NVMe over FC takes advantage of FC’s credit buffer congestion control system.
C. New hardware or infrastructure investment usually isn’t required when using NVMe over FC.
D. All of the above
Answer
D. All of the above
Explanation
It’s true. Any 16 Gbps or 32 Gbps FC HBA or switch will support NVMe over FC, while also providing traditional SCSI over FC services. Because of this, new infrastructure isn’t often necessary when deploying NVMe over FC. An efficient congestion management system is required for any network fabric to consistently deliver NVMe’s low latency. With FC’s credit buffer congestion control system, data isn’t transmitted until the sender gets a buffer allocation from the recipient, ensuring reliable data transport.
Question 6
When it comes to FC vs. Ethernet, which of the following is true?
A. FC is significantly faster than Ethernet.
B. FC supported a lossless, switched-based network topology from the start.
C. FC adoption is beginning to surpass Ethernet.
D. All of the above
Answer
B. FC supported a lossless, switched-based network topology from the start.
Explanation
In terms of speed, Ethernet continues to be the storage networking technology of choice, though the FC vendors are working to catch up with Gen 6 FC. Ethernet’s lower cost and flexibility also have kept Ethernet adoption ahead of FC. FC has provided lossless data transport from the start; that capability was added to Ethernet later in the technology’s evolution.
Question 7
What is FCoE?
A. It’s a protocol that encapsulates FC frames over Ethernet networks.
B. It enables FC traffic to move across high-speed Ethernet networks.
C. It converges the storage networking technologies into one cable transport and interface.
D. All of the above
Answer
D. All of the above
Explanation
FC over Ethernet (FCoE) is a protocol that lets FC and Ethernet traffic share the same physical cable by converging the storage networking technologies into one cable transport and interface. It uses FC’s device communications, substituting high-speed Ethernet links for FC links between devices. However, a lack of end-to-end FCoE devices has limited adoption of the technology.