This operand is used to periodically look (sniff) for a z/OS NFS Server control block chain breakage associated with z/OS UNIX file systems. The sniffer inspects the z/OS UNIX mount control blocks, checking for allocation and linked-list consistency, and creates a dump if it detects a problem (the z/OS NFS Server continues to run after the dump is taken). Enter the operand as follows:

>>-+-MODIFY-+--mvsnfs,cbsniff-+------+-------------------------><
   '-F------'                 '-=nnn-'   

where

nnn

is a value of 0 or a number of seconds from 2 to 86400 (24 hours) specifying the time interval at which the sniffer is to run. If the specified value is larger than the maximum in this range, it is set to 86400. If it is 1, it is set to 2 (to prevent the sniffer from running too often). If it is negative, it is set to 0.

If the sniffer value is set to 0, the sniffer is turned off; otherwise it will be run immediately and then set to the timer period (in seconds) as specified.

If Cbsniff is issued without the equals sign ('='), the sniffer runs one time without altering the period of the sniffer (even if it is off at the time). If it does not identify a problem, any timer period is started anew.

If the sniffer identifies a problem, it generates an SDUMP and turns itself off (no further sniffers unless turned on explicitly).

The sniffer default is 0. It must be explicitly started every time the z/OS NFS Server is started or restarted, including for a SYSPLEX failover, or after the sniffer has triggered and created a dump.