you should see a folder structure ending in CIS\LOGS on the drive where you installed the 5.5 U1 SSO component..
Similar to :-
- vCenter Server 5.5.x on 2003 –
%ALLUSERSPROFILE%\Application Data\CIS\logs\ - vCenter Server 5.5.x and 2008, 2012 –
C:\ProgramData\VMware\CIS\logs\ - vCenter Server Virtual Appliance 5.5.x –
/var/log/vmware/sso/
Once you see those logs you can be confident all is ok, just take your old SSO db offline via SQL for added confidence