The STATUS control statement is used to display usage statistics about the database. These usage statistics are as follows:
- Total blocks
- Total blocks used
- Percentage of utilization
- Cylinders, blocks, used blocks, and error blocks for each data set in the database
- Number of empty blocks (without data) in the database index
You can view a partial set of these statistics.
The high-level name of the database must have been defined with the NAME control statement (or the PARM parameter of the EXEC JCL statement).
STATUSdisplay - optionreserve - option
- display-optionSpecifies FULL to print complete statistics for the database, master index, and data sets, or INDEX to print statistics for the database and master index only, or USED to print the 'percentage used' for the database.If the parameter is omitted, statistics for the database and data sets are printed.
- reserve-optionSpecifies either RESERVE to place a reserve on the database for the duration of the index evaluation process or NORESERVE to not place a reserve on the database.This option is only applicable when specified with the display - option. Because the master index is updated by many tasks, jobs, or online sessions, the master index data can change during the evaluation process, causing inconsistent statistics. The RESERVE option delays external updates to the database for obtaining consistent statistics. If reserve-option is omitted, NORESERVE is assumed.
To compile index statistics information, the entire master index must be read. Depending on the size of the database, this process can take a long time.
Messages Resulting From STATUS
The STATUS statement causes the SARDBA09 messages to be displayed. The meaning of the index statistics displayed in the SARDBA09 messages are as follows:
- Index levelsThe number of levels or hierarchies in the master index.
- Index recordsThe total number of records in the master index.
- Index allocationsThe total number of control areas or segments that comprise the master index.
- Index blocksThe total number of database blocks that comprise the master index.These index blocks can be pointer blocks, data blocks, or free blocks.
- Index used blocksThe total number of database blocks currently being used in the master index.This value includes the index pointer block, the index data blocks, and the index empty blocks.
- Index pointer blocksThe total number of higher level hierarchical index blocks that reference lower level index blocks.
- Index data blocksThe total number of database blocks that comprise the lowest level of the master index, and that contain the physical index data.
- Index empty blocksThe total number of index data blocks that do not contain any index records.When index records are deleted from the master index, the index data is removed from the index data block. When all index records have been removed from the index data block, the index data block is considered empty but available for subsequent use in the same key range. REORG or UNLOAD/LOAD functions of the SARDBASE utility are recommended for a database with a high percentage of empty blocks.
Index File Statistics
Executing the database utility SARDBASE/STATUS FULL creates a report with detailed statistics for the index space. The following is an example of the report.
SARDBA09 Index file statistics: SARDBA09 Block size: 8906 SARDBA09 Total cylinders: 40 SARDBA09 Total blocks: 3600 SARDBA09 Total used blocks: 1440 SARDBA09 Percent utilization: 40 SARDBA09 Total levels: 3 SARDBA09 Total records: 20727 SARDBA09 Total allocations: 16 SARDBA09 Total pointer blocks: 7 SARDBA09 Total data blocks: 183 SARDBA09 Total empty blocks: 0 SARDBA09 Total free blocks: 1249
- Block SizeThe default block size of the index extent is 8906.
- Cylinders Total BlocksTotal blocks represents the number of blocks that were allocated in the total space (number of cylinders) allocated to the index space.
- Used BlocksPercent utilization is a simple calculation of the '(used-free)/total'.Percent utilization does not represent the space used within the individual used blocks as they contain data that is added or removed based on activity to the database.
- LevelsThe number of levels in the index 'tree'.Higher level index blocks contain lower level index block pointers and the lowest level contains the Master Index record data. Thus, three 'levels' would represent two index pointer levels and the Master Index record data level.
- RecordsThis is the total number of Master Index records.Beginning with r11, the number of index records has increased. These records help improve the performance of functions such as the backup cycle.
- Pointer BlocksThe number of blocks which contain lower level index pointers.
- Data BlocksThe number of blocks that contain Master Index data records.
- Empty BlocksA block can be placed in this block pool under certain rare error conditions; under normal circumstances, expect this field to display zero blocks.
- Free BlocksThe number of allocated blocks that were allocated, that is, shown in the number of used blocks, but that are currently empty and available for use when additional blocks are needed.