Basically you have two ways to perform backups. The preferred way with Oracle’s databases today is to use RMAN. The following will perform a hot backup using RMAN:
rman target /
allocate channel t1 type disk format ‘/dir/%d_FULL_%U ‘;
Alternatively, you can place a tablespace in hot backup mode by the following:
ALTER TABLESPACE ts_name BEGIN BACKUP;
Once the tablespace is in backup mode, you can use any OS utility to copy the tablespace’s datafiles to the backup location. Once the tablespace backup is done, end the tablespace backup:
ALTER TABLESPACE ts_name END BACKUP;
Repeat for each tablespace.