Using SMF Data Sets

During initialization, SMF searches the SMFPRMxx parmlib member to see whether the system is using log streams or SMF data sets to record SMF data. If the member specifies or defaults to RECORDING(DATASET), SMF searches the list of data sets specified on the DSNAME parameter of the SMFPRMxx member for the first non-full data set. The search proceeds in the order that the data sets were defined. If a data set is found, that one becomes the ACTIVE data set. The remaining data sets are processed such that any non-empty data set will be set to status of DUMP REQUIRED, and any empty data set will be set to status of ALTERNATE.

If no non-full data set is found, SMF stores the records in its buffers until a data set is made available. To make a data set available, or to empty it, you must run the SMF dump program. For more information, see Using the SMF Dump Programs.

The first data set specified on the DSNAME parameter of the SMFPRMxx parmlib member is called the primary data set and should be allocated on a high performance device; the rest are secondary data sets.

The following examples show the result of a D SMF command issued under different SMF initialization environments.

Data Set Initialization, Example 1:The following example shows the results of initialization when there is 1 non-full and 2 empty data sets.

d smf
IEE949I 11.05.21 SMF DATA SETS 728
  NAME        VOLSER SIZE(BLKS) %FULL STATUS
P-SYS1.MANA SMFVL1       15000   15  ACTIVE
S-SYS1.MANB SMFVL2        300    0   ALTERNATE
S-SYS1.MANC SMFVL2        300    0   ALTERNATE

Data Set Initialization, Example 2: The following example shows the results of initialization when the first data set is full (contains data left over from the previous system IPL) and the second one is non-full.

d smf
IEE949I 11.05.21 SMF DATA SETS 728
  NAME        VOLSER SIZE(BLKS) %FULL STATUS
P-SYS1.MANA SMFVL1       15000  100  DUMP REQUIRED
S-SYS1.MANB SMFVL2        300    1   ACTIVE
S-SYS1.MANC SMFVL2        300    0   ALTERNATE

Data Set Initialization, Example 3: The following example shows the result when the first data set is non-full, and the second and third data sets contain data left over from previous system IPL.

d smf
IEE949I 11.05.21 SMF DATA SETS 728
  NAME        VOLSER SIZE(BLKS) %FULL STATUS
P-SYS1.MANA SMFVL1       15000   20  ACTIVE
S-SYS1.MANB SMFVL2        300    1   DUMP REQUIRED
S-SYS1.MANC SMFVL2        300   100  DUMP REQUIRED

Note that SMF will not switch to a partially used data set, so in the above example even though SYS1.MANB is only 1% full, SMF will not be able to switch to and record on it until it is dumped and cleared.