Chapter 1 Product and Architecture Overview
1-3
1.1.1
Fibre 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.
1.1.1.1
SANnet 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.
