The best way to do this is by looking at performance data and running it through a tool called BCSD. However, if you don't have access to the tool you can use the attached image to calculate the journal size.  [IMAGE]
I need to configure RP for my client as CRR only.  I simplify details as below:  CRR only Source lun = 1TB  Size of daily change (1TB * 15%) = 150GB Only one consistency group for this source lun. No other consistency group.   RTO = 1hrs RPO = 48hrs  How to estimate the journal volume? And any overhead need included?  Hope all of you feedback.  Thanks!
How to estimate the size of journal volume in RP for CRR only