Are host adapters the weakest link in your storage network?

You’re getting ready to hit the road for a camping vacation and you’ve spent a lot of money on your camper and truck. You definitely wouldn’t want to get on the road with a hitch that isn’t made for the job, right? Nevertheless, we often run into data center professionals believing they can get away with it when it comes to storage connectivity. They make a price-based decision, choosing a commodity or an off-brand host bus adapter (HBA) which, in the end, is a recipe for trouble and poor performance.?An investment in storage, servers, network, and other infrastructure is devalued because of a compromised component selection at one of the most important points in the ecosystem.

When people talk about storage performance, they are referring to the speed and efficiency with which data can be read from or written to a storage device. Storage performance is a crucial aspect of computing systems as it directly affects how quickly data can be accessed and processed. Several key factors contribute to storage performance: overall read/write speeds (GB/sec), latency (response time), the ability to handle substantial IOPS traffic, queue depth (pending requests), and data type (sequential versus random, large block versus small, etc.).

Storage performance requirements vary depending on specific use cases. For example, high-performance databases, video editing applications, and virtualization environments typically require storage systems with high read/write speeds, low latency, and high IOPS, whereas general-purpose home computing may have more relaxed performance requirements.

In high-performance storage environments where low latency, high bandwidth, and efficient I/O operations are critical, the HBA's impact on storage performance can be more pronounced. For example, in Fibre Channel-based storage networks, where HBAs are commonly used, the choice of an optimized and high-performance HBA can significantly impact the overall storage system's performance.

Regardless of the application, in each case every single bit of data is passed through the HBA connecting the compute platform (server, workstation, etc.) to the storage. Therefore, when designing a storage network for the best ROI, and to ensure quick payback on this large capital investment, skimping when it comes to selecting the right HBA is a bad decision since HBAs have a direct impact on storage, and, subsequently, system performance in all the places mentioned earlier, and more.

Like anything else, an HBA is the sum of its parts. When assessing the viability of any particular HBA, we need to consider the complete package, which includes not just hardware but software as well, as each has an impact on overall performance.

The HBA plays a crucial role in determining the data transfer speed between the host system and the storage devices. It acts as an intermediary between the host's internal PCIe bus and the storage network. The speed and capabilities of the HBA, such as its supported data transfer rates, can directly affect the overall storage performance. Poor HBA driver design, as well as component selection (i.e. off-brand optical SFP connectors), will adversely impact transfer speeds.

Queue depth refers to the number of pending commands that the HBA can handle simultaneously. A higher queue depth allows for better utilization of the storage system and can improve performance in scenarios with multiple concurrent I/O requests. Command offloading refers to the capability of the HBA to offload certain processing tasks from the host system, reducing CPU overhead and potentially improving storage performance. Queue depth support and command offloading are both impacted by the driver quality as well as hardware options. For example, some HBAs have components specifically included to handle offloads in hardware to improve performance and reduce CPU utilization.

Well-designed and regularly updated drivers can improve compatibility, reliability, and performance by ensuring efficient communication between the host system, HBA, and storage devices. Additionally, when (yes, “when,” not “if”) storage systems encounter errors or encounter issues like lost connectivity or transmission errors, an HBA with robust error handling mechanisms and built-in resilience features can help mitigate these issues and maintain storage performance during such situations.

Just like our trailer hitch is a critically important part of a successful vacation, choosing a high-quality, well-designed HBA is just as important in maximizing storage performance, optimizing ROI, and reducing the headaches that can happen if the HBA is overlooked. The HBA might not be the sexiest part of the storage network, but in many ways, it can be the most important.