It depends. Could you describe your end objective a bit more, and perhaps describe your current and proposed environment (hardware/OS wise) for some more accurate comments? As an overview of my thought process: - Oracle Server s/w is installed in an ORACLE_HOME, which defines one version of s/w and it's patches - Multiple ORACLE_HOMEs are allowed on a server, therefore multiple versions of Oracle s/w are permitted (and may be run concurrently) - One instance is basically the s/w running from one ORACLE_HOME, interworking with one SGA - One ORACLE_HOME "controls" one or more Oracle Database, each with it's own instance - exception: RAC, multiple instances from multiple ORACLE_HOMEs control one database. - The version upgrade process generally encourages two ORACLE_HOMEs, with the new HOME taking over control of an existing database Hope that helps /Hans On 03/10/2012 7:48 AM, Zelli, Brian wrote: > Can I load 11g on an already existing 10g instance? Any gotchas? > ciao, > Brian > -- //www.freelists.org/webpage/oracle-l