FCP Hardware Data Router support

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The latest Fibre Channel Protocol (FCP) devices have hardware data router support. This feature can improve the throughput for FCP/SCSI devices by reducing the path length when transferring the data from memory to an FCP device.

These are the minimum requirements for using the FCP hardware data router with Linux® on z Systems®:
  • zEnterprise® 196 GA2 and zEnterprise 114 with FICON® Express8S.
  • z/VM® 6.3 or later, that introduced guest support for hardware data router.
  • KVM for IBM z Systems®.
  • RHEL 6.4 or SLES11 SP3 (must be manually enabled).
  • For RHEL 7 or SLES12 (are enabled per default).
The command for displaying the availability of an FCP hardware data router for a z/VM guest is:
CP Q V FCP
FCP  1722 ON FCP   1722 CHPID 55 SUBCHANNEL = 0000
     1722 DEVTYPE FCP         VIRTUAL CHPID 55 FCP REAL CHPID 55
     1722 QDIO-ELIGIBLE       QIOASSIST-ELIGIBLE
     1722 DATA ROUTER ELIGIBLE
To enable FCP data router support with a Linux kernel parameter (if not enabled by default):
- set the ‘zfcp.datarouter=1’ Linux kernel parameter
The ways in which the the status of the FCP hardware data router can be displayed in Linux are:
# systool -m zfcp -v
Module = "zfcp"

  Attributes:
    initstate           = "live"
    refcnt              = "48"
    srcversion          = "52F4E65D11CC52E53FD2D0D"
    supported           = "Yes"

  Parameters:
    ...
    datarouter          = "Y"
    ...
or
# cat /sys/module/zfcp/parameters/datarouter
Y
Note: The FCP hardware data router feature becomes active only for FCP devices that are based on adapter hardware with data routing support.