Could you please explain me.
1) How many days backup, by default RMAN stores?
2) From where list & report commands will get input?
3) What is the difference between auxiliary channel and maintenance channel?
Good day Sechu
(1) I don't really know what the default RMAN keep for backup. I always specify my retention policy. I never use the default. Here is some information about RMAN retention policy
(2) It is depending on how you configure your rman. Are you using catalog or not? If you are using catalog, then it will be from the catalog, otherwise, it's the control file.
(3) The definition of the auxiliary channel is as follow according to http://docs.oracle.com/cd/B28359_01/backup.111/b28273/rcmsynta004.htm
"Specifies a connection between RMAN and an auxiliary database instance.
An auxiliary instance is used when executing the DUPLICATE or TRANSPORT TABLESPACE command, and when performing TSPITR with RECOVER TABLESPACE (see Example 2-9). When specifying this option, the auxiliary instance must be started but not mounted.
See Also: DUPLICATE to learn how to duplicate a database, and CONNECT to learn how to connect to a duplicate database instance"
You will be able to find the other channel description ther.