2. PLANNING › 2.3 SMF Requirements › 2.3.1 SMF Requirements (VCC)

2.3.1 SMF Requirements (VCC)

VCC supports SMF as a recording medium.  It produces a
segmented record that follows the SMF record segmentation
conventions (for example, as used by SMF type 30 and RMF type
70-series records) where a segment specifies the offset,
length, and number of occurrences of the next segments.

The choice of using SMF as a recording facility for VCC
depends solely on the size of your installation and the
amount of DASD data VCC is expected to collect.  VCC
generates one SMF record for every:

    o  Format 1 DSCB encountered in a VTOC (every data set).

    o  DASD volume scanned.

    o  VSAM data set found in a catalog.

    o  VSAM alternate index found in a catalog.

    o  VSAM data set found in a VVDS (ICF catalogs only).

    o  VVDS information for VTOC data sets managed by DFSMS.

    o  VSAM alternate index found in a VVDS (ICF catalogs
       only).

    o  VSAM data set found in a VVDS (ICF catalogs only) and
       VVDS information for VTOC data sets managed by DFSMS
       are repeated if a VSAM Volume Record (VVR)
       representing a data set fills up due to extents and
       needs to have a secondary VVR built.

    o  If a VSAM data set's index component has the IMBED
       option specified, a separate record is generated by
       VCC.  This is because the index's sequence set resides
       in the first track of each data component control
       area.  That space is described by a separate record in
       the VVDS, causing another record to be generated by
       VCC.  This is duplicate recording of space utilization
       because the sequence set space is also described in
       the data component extents, but is unique in other
       respects (for example, low RBA, high RBA, etc.).  The
       duplicate recording of space information is ignored by
       the CA MICS Space Analyzer Option.

    o  VSAM master and user catalog.

Let's assume that you have the following:

     10000 VTOC data sets
       100 VSAM clusters and alternate indexes
        10 ICF BCSs including the master catalog
        60 VVDSs (one on each volume with a VSAM data set)
        85 DASD volumes

VCC will then generate at least:

     10000+(100*3)+10+85=10395

SMF records.  Note that VSAM is counted three times for ICF
because there is a VSAM data set entry in the BCS, as well as
a VVDS entry and a VTOC entry.

The average size of each SMF record is variable because of
the variance in the number of extents for each data set and
the variance in volume free space fragmentation from one site
to the next.  In testing the product, the average record size
was found to be approximately 235 bytes.  Using this number,
VCC records generated by the above site will consume about
2.4 million bytes of DASD space.  Using 4K physical SMF
records, this is equivalent to approximately 153 tracks on a
3350, or about five 3350 cylinders.

A consideration that may help you decide between recording
VCC data to SMF or to a data set is the speed at which this
data will be sent to SMF.  VCC is capable of generating
10,000 SMF records to a data set in a little under 20 seconds
of elapsed time running on a lightly loaded 3033U processor.
If this same amount of data is sent to SMF, a period of
system-wide degradation can occur due to SMF buffer
shortages, especially during prime shift peak hours.