Hi Amir, > I am trying to understand if it is expected to see performance > degradation of DML transactions that are active during a hot backup. It > is my understanding that the only noticeable thing that happens during a > hot backup for DML statement is an increase in the amount of redo > generation and that is because Oracle starts to log full images of data > blocks before a change is made to a data block. I am not aware of any > impact on performance while in hot backup mode, unless the LGWR is being > constrained for some reason. My kneejerk is two things: 1) The hot backup will certainly use system resources, especially IO. If your instance is heavy on IO or IO-bound, then the possibly significant IO load of the backup would likely impact Oracle transactions. 2) You may want to consider using RMAN instead of the traditional hot backup. Rich -- //www.freelists.org/webpage/oracle-l