Brocade Communications Systems Network Advisor 12.3.0, User Manual

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Brocade Network Advisor SAN User Manual 949
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FICON emulation features
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FICON emulation features
FICON emulation supports FICON traffic over IP WANs using FCIP as the underlying protocol. FICON
emulation features support performance enhancements for specific applications. If you are using
FCIP for distance extension in a FICON environment, evaluate the need for these features before
you run the FCIP configuration wizard. FICON emulation may be configured by selecting Advanced
Settings on the Add Tunnel or Edit Tunnel dialogs. The following features are available:
•
IBM z/OS Global Mirror (z Gm) emulation.
•
Tape write pipelining.
•
Tape read pipelining.
•
Teradata pipelining
IBM z/OS Global Mirror (z Gm) emulation
The IBM z/OS Global Mirror (z Gm) application, formerly known as eXtended Remote Copy (XRC), is
a DASD application that implements disk mirroring, as supported by the disk hardware architecture
and a host software component called System Data Mover (SDM). The primary volume and the
secondary mirrored volume may be geographically distant across an IP WAN. The latency
introduced by greater distance creates delays in anticipated responses to certain commands. The
FICON pacing mechanism may interpret delays as an indication of a large data transfer that could
monopolize a shared resource, and react by throttling the I/O. IBM z/OS Global Mirror (z Gm)
emulation provides local responses to remote hosts, eliminating distance related delays. A FICON
XRC Emulation License is required to enable IBM z/OS Global Mirror (z Gm) Emulation.
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:
Two 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 Acceleration 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 76 OSTP constraints
FCIP Fastwrite Tape Acceleration