I have two OES2 (SLES10-SP1 + OES2) that i want to upgrade to SLES10-SP4+OES2-SP3.

Is it possible to do a direct upgrade or do i have to do this SP by SP?

Another quiestion:
Servers are located on a remote site. I read that there is possible to do remote upgrade without to be physic on location. How can i do this?