Is there any way to backup Oracle DB in parallel in many tape drives (balanced well and independent of datafile sizes)?
The only one i found is script-based backup with RMAN parameter SECTION SIZE included in script. Which is not as convenient as Oracle Intelligent Policies unfortunately.
Think you can choose number of channels in OIP, the usual way to get RMAN to run parallel streams.
How RMAN balance this nowadays you will have to ask your Oracle DBA about.
Try to look up to the Oracle Tab options if you havn't already
Number of channels is neccessary but not enough condition. It's good if DB consists of some files with equal or near to equal sizes. Each file is binded by RMAN to one exact channel even if you choose to cut it to smaller backup pieces. For example, If it is one large file and some small files, and you set number of channels to 4, then at the beginning RMAN will use all 4 channels. Each file will use one channel. When one file finished, another will use free channel. But when all small files finished, the large file will still use one channel and three channels will be free.
If DB has non equal sizes of files or if some files are really huge and you want to improve their backup performance using parallel streams, then you need to use such RMAN parameter as SECTION SIZE. It allows to divide all data (and big files too) to sections and write them to all free channels.
Unfortunately the Oracle Tab in OIP has no option to set SECTION SIZE.
So, my question is, Is there any way to set this parameter for exact client in RMAN parameters or in NBU Client parameters on client size so that it used for all RMAN sessions (and OIP scheduled backups too)? Or get the same result somehow else?