HP StorageWorks Fabric OS 6.1.1 administrator guide (5697-0235, December 2009)

Fabric OS 6.1.x administrator guide 443
XRC emulation
The eXtended Remote Copy (XRC) application 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. XRC emulation provides local
responses to remote hosts, eliminating distance related delays. A FICON XRC Emulation License is required
to enable XRC Emulation.
Tape Write Pipelining
FICON tape write pipelining improves performance for a variety of applications when writing to tape over
extended distances. FICON tape write pipelining locally acknowledges write data records, enabling the
host to generate more records while previous records are in transit across the IP WAN. If exception status is
received from the device, the writing of data and emulation is terminated. The FICON Tape Emulation
License is required to enable FICON Tape Write Pipelining.
Tape Read Pipelining
FICON tape read pipelining improves performance for certain applications when reading from FICON
tape over extended distances. FICON tape read pipelining reads data on the tape directly from the tape
device. Reading of tape continues until a threshold is reached. The buffered data is forwarded to the host
in response to requests from the host. When the host sends the status accept frame indicating that the data
was delivered, the read processing on the device side credits the pipeline and requests more data from the
tape. If exception status is received from the device, the reading of data and emulation is terminated. The
FICON Tape Emulation License is required to enable FICON Tape Read Pipelining.
FICON emulation configuration
Before you configure FICON emulation, you will need to understand the available options, and if those
options are to be implemented in your installation. If FICON emulation is new to you, please read ”FICON
emulation concepts and features” on page 442 in this chapter. The syntax for the portcfg ficon
command is as follows:
portCfg ficon [slot/]ge0|ge1 tunnel_Id config [-x 1|0] [-w 1|0] [-r 1|0] [-t 1|0]
[-l 1|0] [-b 1|0] [wrtMaxPipe value] [rdMaxPipe value] [wrtMaxDevs value]
[rdMaxDevs value] [wrtTimer value] wrtMaxChains value] [oxidBase value] [dbgFlags
value]
where:
• slot is the number of a slot in a Director chassis that contains an FC4-18i blade. This parameter does
not apply to the stand-alone 400 MP Router.
• ge0|ge1 is the Ethernet port used by the tunnel (ge0 or ge1).
• tunnel_id is the tunnel number (0 - 7).
• config is the option that creates a configuration.
• -x 1|0 enables or disables XRC emulation. 1 is enable, O is disable.
• -w 1|0 enables or disables tape write pipelining. 1 is enable, O is disable.
• -r 1|0 enables or disables tape read pipelining. 1 is enable, O is disable.
• -t 1|0 enables or disables TIN/TIR emulation. 1 is enable, O is disable. This option should be
enabled when one or all of the following features are enabled:
•XRC emulation.
• tape write pipelining.
• tape read pipelining.
• -l 1|0 enables or disables device level ACK emulation. 1 is enable, O is disable. This option should be
enabled when one or all of the following features are enabled:
•XRC emulation.
• tape write pipelining.