what is recovery log ?what are the modes of recory log ?

A recovery log is what ever transactions happened to the database tht transaction related records are recorded in the recovery log. one the data is committed to the database recovery becomes empty. this is normal mode.

Roll forward mode: once the transaction is committed to the database all the transaction related records are stored in the recovery log until we take the Db backup.

The advantage of normal mode it requires less memory

The disadvantage is we can’t recover the database to the most current state.

The advantage of roll forward is we can recover the database to the current state hwen it was went down,The disadvantage is it requires more space.