Since 4 GB Fibre Channel (FC) was introduced, there have been significant changes in data centers, including server...
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virtualization, a focus on power and cooling, and the rapid acceptance of solid-state disk (SSD). These factors, combined with the never-ending need for greater performance and scalability, will cause a faster adoption of 8 GB FC than the shift from 2 GB to 4 GB FC.
Virtualization has radically changed the way physical hardware accesses storage resources. Prior to virtualization, the entire relationship was one-dimensional; one physical server, running one application, connected to a single (although redundant) storage-area network (SAN) connected to a single logical unit number (LUN) on a SAN. Now multiple applications are running on a single host, through one or multiple storage interfaces to multiple LUNs on potentially multiple SAN arrays.
This creates two problems that are solved in large part by 8 GB FC. The first is a performance issue. Thirty virtual hosts sharing a finite number of storage connections to storage will benefit from the extra bandwidth. Space for additional host bus adapters (HBAs) is always an issue in server virtualization rollouts, especially when considering blade servers. And 8 GB FC greatly reduces the HBAs required.
Then consider N_Port ID Virtualization (NPIV). This is a Fibre Channel enabler that allows multiple N_Port IDs to share a single physical N_Port. This lets multiple FC initiators occupy a single physical port, easing hardware requirements in storage-area network design, especially where virtual SANs are called for. NPIV allows customers to effectively "virtualize" SAN connections so that each virtual machine has independent access to its own protected storage. This provides additional benefits, including the ability to track and charge back the storage utilization at the virtual machine level.
Most performance walls are climbed by adding additional HBA cards to the servers, additional storage I/O paths to the storage controllers or a greater number of storage controllers. Yet each of these steps consumes FC switch ports, which increases your investment in physical switches. The more physical switches there are, the more switch interconnections you have, which also consumes switch ports.
All of the additional HBAs, storage ports and storage controllers result in additional port consumption. This impacts costs in three ways: the expenditure on the physical hardware, the power consumed by each of the additional components, and the extra power and cooling costs associated with each component.
Performance improvement has always motivated users to upgrade to the next generation of FC technology, and 8 GB is no different in this respect. What is different for 8 GB FC is the emergence of solid-state disk. In generations past, there were incremental upgrades to drive technology -- 10K rpm drives to 15K rpm drives, for example, to take advantage of the faster generation of Fibre Channel. However, most of the performance advancement has come from the storage systems level. In the 4 GB generation, techniques like making a large drive count array group safer via RAID 6, wide striping brought about by storage virtualization, and using data placement intelligence to move active data to very fast areas of the hard drive mechanism all raised the performance capabilities of systems and 4 GB FC was there to deliver it.
Solid-state disk dramatically changes the performance deliverable from the storage system. Because SSDs are as much as 30x faster than mechanical drives, they not only take advantage of 8 GB FC, they almost demand it. For example, one vendor saw an immediate performance increase of 50% by merely inserting an 8 GB HBA into their SSD system.
Solid-state disks are not a new technology, but they had been deemed a niche technology. Yet due to their ever-decreasing price point -- a 2 TB Flash SSD is now less than $150,000 -- the use of solid-state disk is broadening. The price point for SSD is still higher than for mechanical hard drives. But when that investment is made, it is to solve a specific performance problem. Any unused performance capabilities of the technology lower the impact of solid-state disks, but 8 GB Fibre Channel brings the maximum bandwidth to SSDs.