Dot Hill Systems II 200 FC service manual Fibre Channel and SATA Array Architectures

1.1.1Fibre Channel and SATA Array Architectures

The FC, SATA, and SATA SE share many architectural elements. This section discusses those elements, making note of the few ways in which the architecture is implemented differently in the two arrays.

The SANnet II 200 FC array, SATA array, and SATA SE array RAID controllers have six FC channels. RAID controller channels 0, 1, 4, and 5 are normally designated for connection to hosts or Fibre Channel switches. RAID controller channels 2 and 3 are dedicated drive channels that connect to disks. Each channel has a single port connection, except the SANnet II 200 SATA array, which has two extra ports (two connections for channels 0 and 1).

In a dual RAID controller configuration, the architecture of the loops within the chassis provides both RAID controllers the same host channel designators. Each host channel of the top RAID controller shares a loop with the matching host channel on the bottom RAID controller. For example, channel 0 of the top RAID controller shares the same loop as channel 0 of the bottom RAID controller. This provides four distinct loops for connectivity. The individual loops provide logical unit number (LUN) failover without causing host bus adapter (HBA) path failover in the event of a controller failure.

In a single RAID controller configuration, the lower I/O board has drive channels but does not have host channels. Overall, the same number of loops are available, but with only half as many host channel ports. All six fibre channels in a SANnet II 200 FC array’s I/O controller module support 1-Gbit or 2-Gbit data transfer speeds.

1.1.1.1SANnet II 200 FC Array Features

On the SANnet II 200 FC array, RAID controller channels 0, 1, 4, and 5 are normally designated host channels. Any host channel can be configured as a drive channel. In a dual-controller configuration, each host loop includes two ports per loop, one port on the top controller and one port on the bottom controller.

SANnet II 200 FC RAID controller channels 2 and 3 are dedicated drive channels that connect to expansion units. Each I/O board has two ports designated as disk drive loops. These ports connect to the internal dual-ported FC disk drives and are used to add expansion units to the configuration.

The two drive loop ports on the upper I/O board form FC loop 2 (channel 2) while the two drive ports on the lower I/O board form FC loop 3 (channel 3). FC loop 2 provides a data path from both RAID controllers to the A loop of the internal disk drives, while FC loop 3 provides a data path from both RAID controllers to the B loop of the internal disk drives.

Chapter 1 Product and Architecture Overview 1-3