XCF_FDI

Description:

The Failure Detection Interval (FDI) is the amount of time that a system can appear to be unresponsive before XCF will take action to remove the system from the sysplex. Internally we refer to this as the effective FDI, externally it is often designated by the word INTERVAL (referring to the INTERVAL parameter in COUPLExx and on the SETXCF COUPLE command). Check that the effective FDI meets the following requirement:

SpinFDI <= EffectiveFDI <= MULT*SpinFDI + INC

Reason for check:

It is recommended that the user let the system default the effective FDI to the SpinFDI by not specifying the INTERVAL keyword. The INTERVAL keword allows customers to specify an effective FDI that is larger than the Spin FDI. When specified, the INTERVAL value should be at least as large as the SpinFDI to give the system enough time to resolve a spin loop timeout before it gets removed from the sysplex but no so large that the rest of the sysplex suffers sympathy sickness. See message IXCH0510E for a detailed discussion of best practice for FDI.

z/OS® releases the check applies to:

z/OS V1R4 and later. Note, however, that the check has been updated for z/OS V1R11.

Parameters accepted:

MULT (must be an integer in the range of 1 to 9)
INC (must be an integer in the range of 0 to 86400)

User override of IBM® values:

The following shows the default keywords for the check, which you can override on either a POLICY statement in the HZSPRMxx parmlib member or on a MODIFY command. This statement may be copied and modified to override the check defaults:

UPDATE CHECK(IBMXCF,XCF_FDI) 
SEVERITY(MED) INTERVAL(004:00) DATE('date_of_the_change')
PARM('MULT(2),INC(5)') 
REASON('Your reason for making the update.')

Reference:

For more information, see z/OS MVS Setting Up a Sysplex.

Messages:

This check issues the following exception messages:

IXCH0510E
IXCH0206E

See the IXCH messages in z/OS MVS System Messages, Vol 10 (IXC-IZP).

SECLABEL recommended for MLS users:

SYSLOW