HP Surestore 64 FW 05.01.00 and SW 07.01.00 HP StorageWorks SAN High Availabil - Page 75
ISL bandwidth limitation
View all HP Surestore 64 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 75 highlights
Planning Considerations for Fibre Channel Topologies ■ Although the B_Port connection (ISL) between the director and switch is a 1.0625 Gbps serial connection, burst transmissions from multiple FC-AL devices are multiplexed and buffered (the link BB_Credit value is eight), and may coexist in the link. Therefore, the sum of the bandwidths of all devices contending for B_Port access should not exceed 1.0625 Gbps. Exceeding the total bandwidth may result in degraded performance, as shown in Figure 32. Arbitration Cycle Idle Burst Data (D1) Burst Data (D2) Burst Data (D3) Burst Data (S1) H_Ports D1 (30 MBps) S1 (10 MBps) D2 (30 MBps) D3 (30 MBps) ISL (1 Gbps) B_Port Figure 32: ISL bandwidth limitation Three 30-megabyte per second (MBps) tape drives and one 10-MBps server are attached to a switch. Each device uses only a portion of the bandwidth of its respective H_Port connection. Each H_Port connection illustrates four arbitration cycles (each cycle won by a single device), one cycle of burst data transmission, and three idle cycles. The B_Port connection to a director (ISL) transmits multiplexed burst data from all four devices, for which the summed bandwidths equal the 1.0625 Gbps capacity of the link. Therefore, connection of additional devices to the switch adversely impacts B_Port performance. SAN High Availability Planning Guide 75