The Archive log directory is configured with archive_command parameter and set to a local location on client to perform log backups. For more information, refer Configuring the PostgreSQL Archive Log Directory.
Commvault recommends to schedule several log only backups between full backups. To create automatic schedule, see Creating an Automatic Schedule for Database Log Backups.
To delete the transaction log files, see Enabling PostgreSQL Archive Log Deletion after Backup. If Archive Delete check box is not selected, the Commvault software does not prune the logs.
Access to the Media Agent is restricted to the Commvault installation group. If the PostgreSQL user is not a member of this group, log dumps to the disk cache fails. To ensure proper access, make sure to assign the correct UNIX group during installation. For more information, see Preinstallation Checklist for the PostgreSQL Agent on UNIX.