Whenever a tablespace is in hot backup mode, Oracle logs the entire image of the block into the Online redolog files.
My question is does oracle logs the image before it is changed or after the block is changed ?...

and one more question is, when i add a new datafile to the Tablespace which is in hotbackup mode is this datafile also in backup mode ?...
what abt the blocks or extents which get allocated to this datafile ??

anbody has got any idea ?