Installation and Configuration Supplement

SPM Logging

The SPM maintains a log in which it records information about connections, and UOW status. This log is contained in the spmlog directory which is a sub-directory of sqllib. This directory is created the first time that the SPM is started.

The SPM log consists of the following files and directories:

SPMLOG - this is the log directory, under sqllib.
SPMLOG.LCF - this is the log control file.
SPMLOGSD - this is a sub-directory under spmlog which contains the primary and secondary log files:
- SPM00000.LOG - the first primary log file.
- SPM00001.LOG - the second primary log file.
- SPM00002.LOG - the third primary log file.
- SPM00003.LOG - the first secondary log file.
- SPM00004.LOG - the second secondary log file.

SPM Log File Size

The SPM_LOG_FILE_SIZE database manager configuration parameter defines the number of 4K pages of each primary and secondary log file, and it can have the following values:

Minimum - the minimum value is 4.
Maximum - the maximum value is 1000 (4M bytes).
Default - the default is 256 (1M byte).

The log normally only uses the primary extents which are allocated when the log is created. Secondary extents are allocated on demand when log space is constrained. Secondary extents are usually deleted during normal shutdown of the logger.

The SPM log size should be large enough so that performance is not adversely affected but small enough so that space is not wasted. The size that is required depends on the number of transactions using protected conversations and how often commit/rollback is issued. The SPM takes a checkpoint every time DB2 is started and stopped and when the log is 50% full. If the log is too small, the checkpoint process may be invoked often enough to impact performance. The log is probably too small if secondary log files are allocated. If the log is too large, then space will be wasted.

You should use the default log size to begin with.

Changing the SPM Log File Size

The size of the SPM log can be changed when the database manager is stopped and there are no in doubt transactions. The following procedure can be used:

Use the LIST DRDA INDOUBT TRANSACTIONS command to determine whether there are indoubt transactions for which the SPM is responsible. Note that, before issuing LIST DRDA INDOUBT TRANSACTIONS, the application must be connected to the Syncpoint Manager (SPM) instance - use the SPM_NAME database manager configuration parameter as the dbalias on the CONNECT statement. DB2 clients must be at Version 2.1.2 or higher to use the WITH PROMPTING capability of LIST INDOUBT.
If there are some indoubt transactions, stop the database manager:
```
   db2stop
```
Update the Database Manager Configuration with a new SPM_LOG_FILE_SIZE value. For example, to double the log size from the default of 256 * 4K pages:
```
   db2 update dbm configuration using spm_log_file_size 512
```
Go to the sqllib directory and delete the current SPM log. For example, on AIX:
```
   rm -fr spmlog
```
Start the database manager:
```
   db2start
```
A new SPM log of the specified size will be created during DB2 start-up.

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