IBM DS8000 manual Fibre Channel device adapter, New four-port host adapters

12.3.2 Fibre Channel device adapter

The DS8000 still relies on eight DDMs to form a RAID-5 or a RAID-10 array. These DDMs are actually spread over two Fibre Channel loops and follow the successful approach to use AAL. With the virtualization approach and the concept of extents, the DAs are mapping the virtualization level over the disk subsystem back end. For more details on the disk subsystem virtualization refer to Chapter 5, “Virtualization concepts” on page 83.

To host servers
Adapter		Adapter		DA
Processor	Memory	Processor	PowerPC
			server
Adapter		Adapter
			Fibre Channel	Fibre Channel
			Protocol Proc	Protocol Proc
			2 Gbps Fibre Channel ports

Figure 12-4 Fibre Channel device adapter with 2 Gbps ports

The new RAID device adapter is built on PowerPC technology with four 2 Gbps Fibre Channel ports and high function, high performance ASICs. Each port provides up to five times the throughput of a previous SSA-based DA port. Each single Fibre Channel protocol processor satisfies both Fibre Channel 2 Gbps ports at full speed.

Note that each DA performs the RAID logic and frees up the processors from this task. The actual throughput and performance of a DA is not only determined by the 2 Gbps ports and hardware used, but also by the firmware efficiency.

12.3.3 New four-port host adapters

Before looking into the heart of the DS8000 series, we briefly review the new host adapters and their enhancements to address performance. Figure 12-5 on page 261 depicts the new host adapters. These adapters are designed to hold four Fibre Channel ports, which can be configured to support either FCP or FICON. They are also enhanced in their configuration flexibility and provide more logical paths, from 256 with an ESS FICON port to 2,048 per FICON port on the DS8000 series.

Each port continues the tradition of providing industry-leading throughput and I/O rates for FICON and FCP.

Note that a FICON channel can address up to 16,384 devices through a FICON port. The DS8000 series can hold up to 65,280 devices and you need at least four additional FICON channel ports to reach all potential volumes within a DS8000 disk storage server. With four

260DS8000 Series: Concepts and Architecture