Locks             (VSAM)

DESCRIPTION
"Locks" shows the total number of times a file required locking to process data
on a particular "Dataset". There are two kinds of file locks:  record locks and
control interval (CI) locks. The "Locks" datapoint counts only the latter. Since
a CI can contain multiple records, or even portions of records, record locking 
is implicit in a CI lock. A CI lock occurs when an application program requests 
a record (contained inside a CI) from a file, whether for read or for write. 


VALUES
The value of "Locks" ranges from 0 to n, where n depends on how frequently
application programs lock a "Dataset".


INTERPRETATION
This datapoint helps determines how heavily a file is used.  For example, if 
the lock count is high and the transactions that access the file tend to run 
slowly, it is possible that transactions are waiting on each other due to 
CI resource contention. This could indicate a database design problem or an 
application program problem in how, or in what sequence, the data is accessed.


CONCLUSIONS
The number of "Locks" and "Unlocks" should always be the same when no
transactions are executing. If this is not the case, an internal Sun MTP problem
has occurred. The system should be shutdown and restarted. If this situation
repeats itself, please inform Sun support personnel.
