Server Consolidation; Server Consolidation; Isl Bandwidth Limitation - HP 316095-B21 - StorageWorks Edge Switch 2/24 Planning Manual

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.

Server Consolidation

Providing fabric connectivity for multiple low-bandwidth servers (Windows NT
or UNIX-based) by attaching them individually to an expensive Fibre Channel
director is not a cost-effective solution. A practical solution is to consolidate the
servers on an inexpensive loop switch, and then connect the switch to a single
director or edge switch E_Port.
Figure 33
through one B_Port connection to a director. Each server has a 10-MBps
bandwidth, therefore, the sum of the bandwidths of all consolidated servers equals
the B_Port bandwidth of 1.0625 Gbps. Connecting another server to the switch
would exceed the B_Port capability and adversely impact director-to-switch link
performance. Other devices (such as tape drives) should not be connected to a
switch used for server consolidation.
SAN High Availability Planning Guide
Arbitration Cycle
Idle
Burst Data (D )
1
Burst Data (D )
2
Burst Data (D )
3
Burst Data (S )
1
ISL (1 Gbps)
B_Port
illustrates the consolidation of ten servers (using two unmanaged hubs)
Planning Considerations for Fibre Channel Topologies
H_Ports
D (30 M ps) B
1
S (10 M ps) B
1
D (30 M ps) B
2
D (30 M ps) B
3
77