we are using ECC6.0 . our kernel , support packages are very old (2 .5 years back patches ) we don't have test /sandbox system . ours is a 3 system landscape . When the topic of upgrdation started , my suggestion is to add a sandbox to the existing landscape . my idea is , - Making a System copy from production to sandbox -so that i can upgrade each component in sandbox first , i can see the impact and knew the problems that would occur , which would make it easy while upgrdaing the production . is this idea good and correct ? please comment me based on your experiences ... in that case if i am going for a system copy then , - will i get all the clients in the production (or) is there any choice of selecting one client -can users use the production server during the system copy waiting for your suggestions and ideas