Even though host bus adapters (HBA) are integral to effective enterprise data storage, some storage administrators, when they first hear the term HBA, think it's a type of business degree. But they soon realise that they need to be well-versed in how HBAs work and how HBAs can be used for optimal data storage.
An HBA is a hardware device, such as a circuit board or integrated circuit adapter, that provides I/O processing and physical connectivity between a host system, such as a server and a storage device. The HBA transmits data between the host device and the storage system in a storage area network (SAN) and relieves the host microprocessor of the tasks of storing data and retrieving data. The result? Improved server performance.
HBAs are most commonly used in Fibre Channel SAN environments and are also used for connecting SCSI and SATA devices. The emergence of iSCSI has led to the development of another type of bus adapter, the Ethernet HBA.
HBAs integral to SANs
"The HBA is an integral part of the SAN environment," says Bob Laliberte, an analyst at Enterprise Strategy Group. "Typically the HBA will be recognised by the SAN management software. In order for a server to be provisioned storage, it needs to have a connection to that storage. The HBA is one of the components that need to be configured properly in order to provide that connection."
When selecting HBA products, storage managers should evaluate performance, reliability, security, power and server virtualisation capabilities, says Amit Vashi, vice president of marketing at HBA provider QLogic. Another criteria, particularly for enterprises running servers from multiple vendors, is whether the HBAs have broad operating system support, he says, adding that storage managers should look for an HBA that supports all hardware platforms and operating systems.
Organisations should also select an HBA technology platform that provides a common driver architecture across multiple generations, says Scott McIntyre, vice president of customer marketing at HBA vendor Emulex. "This ensures seamless management of all the HBAs throughout the SAN, which is critical in data centre environments with hundreds or thousands of servers attached to external storage," he says.
Does it make sense to implement HBAs from more than one vendor? According to Laliberte, standardising on a single HBA vendor simplifies the management of these devices. "Centralised management in large environments -- think hundreds or thousands of servers, each with multiple HBAs -- is critical," he says. "Trying to upgrade them all, either a patch or software enhancement, can be very difficult. Centralised management software from HBA vendors can help."
Ensuring proper interoperability of HBAs is a challenge, Laliberte says, but that task should be taken care of by the vendors.
HBAs for Fibre Channel SANs currently support data rates of up to 8 Gbps, but future products will support rates of 16 Gbps and 32 Gbps. "In general, they are getter faster and costs are remaining relatively flat for the increased performance," Laliberte says. "Overall, there is more effort being put into them to make them easier to manage: single console, automated patch and upgrade capabilities." Vendors are also trying to place more intelligence in the HBA for greater manageability, he says.
Other trends in the HBA arena include increased security capabilities and the support of server virtualisation. Offering security technology, such as encryption and authentication, has generally not been a priority with HBAs, Vashi says. But that will change as it becomes more common to run Fibre Channel over Ethernet (FCoE).
Virtualisation poses challenge to HBA vendors
The biggest challenge with HBAs today is dealing with virtualisation, particularly gaining visibility into virtualised server environments, Laliberte says. Virtualisation adds a layer of complexity to HBAs, "because it allows multiple applications to be abstracted. There is no longer a 1:1 relationship with application to server. In many cases, there could be five or more applications on a single server sharing an HBA," he added.
And with the mobility options available in virtualisation, applications could actually be migrated from server to server, Laliberte says, making it more difficult to identify applications that require storage.
With virtualisation multiple virtual machines can be loaded onto a single physical machine with one or two HBAs, Laliberte says. In the past, with a one-to-one (i.e., one application to one server) infrastructure, management tools would associate the HBA to the application manually. But now there can be many applications going through a single HBA, and the difficulty arises in trying to manage that environment. How do you know where the applications are? N-Port ID Virtualisation or NPIV is a technology now being adopted in HBAs that enables the HBA to create a separate multiple logical ports for the multiple virtual machines that can then be easily identified as they migrate between servers.
The increasing popularity of server virtualisation and the growing use of blade servers are driving demand for storage, and that translates into greater need for SAN connectivity solutions, such as HBAs, McIntyre says. "We are seeing additional server tiers tapping into SANs because of these trends," he adds.
The leaders in the HBA market are acknowledged to be QLogic and Emulex. QLogic supplies a range of storage networking products, including Fibre Channel HBAs for standard servers and blade servers, Fibre Channel switches, Fibre Channel stackable switches, iSCSI HBAs and iSCSI routers. The company also provides InfiniBand switches and InfiniBand host channel adapters for the emerging high-performance computing market. Emulex offers an array of standard Fibre Channel HBAs, supporting data rates from 2 Gbps to 8 Gbps. The company also sells HBAs for blade servers. Emulex also provides HBA management software, such as HBAnyware, a management suite that enables organisations to update and manage all the HBAs in a SAN, either locally or remotely.
According to Laliberte, there's not a lot of difference between QLogic and Emulex HBAs. Both vendors seem to be on almost an identical product development track. Laliberte says he would give Emulex a slight edge in ease-of-use by virtue of its HBAnywhere software. However, he noted, QLogic offers a wider range of products, with SAN switching, a bigger bet on iSCSI and InfiniBand, and so can offer SAN starter kits and drive into the high-performance computing (HPC) market.
Other HBA vendors include LSI, Atto Technology and Brocade Communications Systems, which entered the HBA marketplace in 2007 with devices for Fibre Channel SANs.
All these vendors can expect to see increased demand for HBAs. A 2007 report by Dell'Oro Group forecasts that shipments of HBA ports will grow significantly over the next five years as blade server producers shift the manufacturing of HBA cards to vendors, such as Emulex and QLogic.