Database July 2015 CPU Query

Hi,

After applying patches July 2015 Patches on our development 12.1.0.2.0 database

1. 20831110 : DB Patch Set Update 12.1.0.2.4 (JUlL2015)

2. 21068507 : Oracle JavaVM Component 12.1.0.2.4 Database PSU (JUL2015)

Post installation instructions include

$ rman catalog rman/cat@rmcat

RMAN> upgrade catalog;

My query is that if I upgrade the catalog .

1. Will this change prevent our other databases (which are both 11g and 12c (but not yet patched) ) continue to backup normally.

2. Also do I only need to run this command once and not for every database that I will be patching.

Thanks.

Pali