Solution : https://service.sap.com/sap/support/notes/1433781 (SAP Service marketplace login required)
Key words : 
terms system copy r3load migration db6 dbsize, <exportlocation>/abap/db/db6/dbsize, <exportlocation>/abap/db/ddldb6, xml r3szchk reason, sap system id, system copy, source system, target system, tablespace names, -sapsid>#<ts-
Related Notes : 
       
| 1490838 | System Copy for Systems based on SAP NW 7.0 incl. EHP 3 | 
| 1339717 | Hom./Het.System Copy SAP NW 7.0 incl. EHP 2 | 
| 1317500 | Hom./Het.System Copy SAP NW 7.0 incl. EHP 1 SR1 | 
| 1238351 | Hom./Het.System Copy SAP NW 7.0 incl. Enhancement Package 1 | 
| 1120872 | Hom./Het.System Copy SAP NetWeaver 7.0 SR3 | 
| 1042437 | Hom./Het.System Copy for SAP NetWeaver Based on Kernel 7.10 | 
| 971646 | 6.40 Patch Collection Hom./Het.System Copy ABAP | 
| 970518 | Hom./Het.System Copy SAP NetWeaver 7.0 (2004s) SR2 | 
| 870863 | (OUTDATED) Hom./Het.System Copy SAP NetWeaver 2004s | 
| 713685 | Hom./Het.System Copy SAP Web AS 6.40 |