Tape streaming is not happening while performing RMAN tape backup. On investigation, you find that it is not because of the incremental backup or the empty file backup and that RMAN is sending data blocks to the tape drive fast enough.
What could be a solution to make tape streaming happen during the backup?
A. Configure backup optimization
B. Configure the channel to increase MAXOPENFILES
C. Configure the channel to increase the capacity with the RATE parameter
D. Configure the channel to adjust the tape buffer size with the BLKSIZE option
A B 选项明显错误，备份优化是用来跳过只读表空间的，MAXOPENFILES 是在多路复用中使用的参数，在每个备份集中的文件数目。
D 选项 BLKSIZE ，这个参数用来指定每个通道为磁带读写分配的默认 buffer 大小。这个大小默认和平台有关。此题中 RMAN 已经将块发送到了磁带设备，设置此参数关系不大，错误。
C 正确，RMAN 发送速度太快，超过了磁带驱动的处理能力，导致磁带驱动阻塞卡主。可以设置 rate 参数设置美标从通道读取的字节数，减少 RMAN 磁盘带宽，可以提升磁带备份的性能