Transaction log files

Distributed transactions that require two-phase commit are only available if transaction log files are used. These log files store information about distributed transactions while they are in progress. Entries are added to the log files when a distributed transaction commit begins and are removed once the transaction has completed. Entries are written to the log files during the prepare phase of a two-phase commit and remain until the entire two-phase commit process has completed.

The benefit of using transaction log files is that a transaction can be completed if one of the servers is interrupted during the transaction. Do not delete transaction log files. Doing so can leave the databases in an inconsistent state if one or more distributed transactions are in process.

Two transaction log files are required to log distributed transactions. By default, these are named tranlog1 and tranlog2, and are located in the subdirectory /QIBM/UserData/WebAS5/product/instance/tranlog/appServer (where product is either Base or ND, instance is the name of your WAS instance and appServer is the name of your application server). The tranlog subdirectory is created during the WebSphere installation process. The log files are created the first time the application server is started. Subsequent starts of the application server use the same transaction log files. The log files are 1 megabyte (MB) in size, each.

Normally, you do not need to change the defaults. However, they can be changed through the WebSphere administrative console. (For more information, see Transaction service settings. ).

If you change the default transaction log directory, the directory that you specify must have these authorities:

• *PUBLIC *RX
• QEJB *RWX
• QEJBSVR *RWX

On the iSeries command line, run the Change Authorities (CHGAUT) command to set the appropriate authorities:

• CHGAUT OBJ('directory') USER(*PUBLIC) DTAAUT(*RX)
• CHGAUT OBJ('directory') USER(QEJB) DTAAUT(*RWX)
• CHGAUT OBJ('directory') USER(QEJBSVR) DTAAUT(*RWX)

where directory is the fully qualified path name of the directory.