15. Performing Backup and Recovery : Journals : Database Characteristics Affected by Alterdb : Journal File Size
 
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Journal File Size
Journal files are created by the archiver process by the first journal write after a checkpoint takes place. Additional journal files are created as prior files are filled.
By default, journal files are created with:
A target number of journal blocks of 512
A block size of 16384 bytes
An initial allocation of 4 blocks
This results in a target journal file size of 8 MB (16384 * 512 bytes). Although most users find these parameters satisfactory, all three can be modified by using the alterdb utility.
The alterdb command has the following syntax for altering block sizes:
alterdb dbname -target_jnl_blocks=n | -jnl_block_size=n | -init_jnl_blocks=n