HP StorageWorks Fabric OS 5.3.x administrator guide (5697-0244, November 2009)

Fabric OS 5.3.0 administrator guide 399
Supported configurations
To help understand the supported configurations, consider the configurations shown in the two figures
below. In both cases, there are no multiple equal-cost paths. In Figure 33, there is a single tunnel with
fastwrite and tape pipelining enabled. In Figure 34, there are multiple tunnels, but none of them create a
multiple equal-cost path.
Figure 31 Single tunnel, fastwrite and tape pipelining enabled
Class 3 traffic is accelerated with fastwrite. Class 3 traffic is accelerated between host
and sequential device.
With sequential devices (tape drives), there
are 1024 initiator-tape (IT) pairs per GbE
port, but 2048 initiator-tape-LUN (ITL) pairs
per GbE port. The ITL pairs are shared among
the IT pairs. For example:
• 2 ITL pairs for each IT pair as long as the
target has two LUNs.
• If a target has 32 LUNs, 32 ITL pairs for IT
pairs. In this case, only 64 IT pairs are
associated with ITL pairs.
The rest of the IT pairs are not associated
to any ITL pairs, so no tape pipelining is
performed for those pairs. By default, only
fastwrite-based acceleration is performed
on the unassociated pairs.
Does not support multiple non-equal-cost path
between host and sequential device
Table 99 Using fastwrite and tape pipelining (continued)
Fastwrite Tape pipelining
Connection can be
VE-VE or VEX-VE