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v NUM_LOG_SPAN
LOGFILSIZ, LOGPRIMARY, LOGSECOND
At a minimum, configure 20 transaction logs (LOGPRIMARY=20) of 256 MB
(LOGFILSIZ=65536 4K-pages) for Sterling B2B Integrator.
As an additional precaution, configure at least 12 secondary transaction logs
(LOGSECOND=12). DB2 allocates secondary logs when it cannot reuse any of the
primary logs due to active transactions.
Track the following monitor elements to assess the effectiveness of these settings,
and adjust as needed:
v total_log_used and tot_log_used_top to see how much of the logs are used
v Which workloads are consuming or holding the transaction logs when
LOGPRIMARY approaches the total primary log capacity. If needed, raise the
setting for LOGPRIMARY.
v sec_log_used_top and sec_logs_allocated to see if secondary transaction logs are
used. Investigate how often logging spills over to the secondary logs and what
workloads are running during the spill. If needed, increase LOGPRIMARY to
prevent log spills.
NUM_LOG_SPAN
This parameter limits the number of logs a transaction can span, which prevents
situations where DB2 cannot switch transaction logs because all the transaction
logs are active. For example:
v Someone may have updated a record in IBM Sterling Control Center, but may
have forgotten to commit the change.
v Updates to one or more database records might not get committed due to a
software bug.
Set NUM_LOG_SPAN to a minimum of 12 so that valid long-running transactions
are not prematurely forced, and a maximum of LOGPRIMARY minus a safety
buffer. For example, if LOGPRIMARY=20 and you decide upon a safety buffer of 4,
the maximum NUM_LOG_SPAN=16.
DB2 Monitoring
DB2 includes many facilities for tracing system activity at just about any level of
detail. This section covers the following topics:
v Snapshot Monitors
v Snapshot Monitor Commands
v DB2 Event Monitors
v Use an Event Monitor to Diagnose and Flush Deadlocks
v DB2 Performance Expert
Snapshot Monitors
Information about snapshot monitors is available by searching at
http://www.ibm.com/developerworks/.
Snapshot monitors collect information about the state of a DB2 instance and any
databases it controls at a specific point in time. Snapshots are useful for
determining the status of a database system. When taken at regular intervals, they
48 Sterling B2B Integrator: Performance Management