Each backup tool vendor ships their own agent, but the agents are only required if you want to use their software in a specific way. For example, Oracle's RMAN backup tool requires the Oracle Intelligent Agent if you will be scheduling backups from Oracle Enterprise Manager. This is because OEM requires OIA. RMAN does not. I use RMAN without OIA from the MS-DOS command prompt. Unless I am forgetting something, the OIA is not necessary for piping data to the OBSI / ADSM device.