Hi all, I would like to create a few attributes in our Win2008R2 AD schema, and add new attributes into User and OrganizationalUnit Class. Question 1: Can I do this operate in working time? Is it affect our AD service? Question 2: Before I do this, what should I backup? Thank you very much. BR Guo YingHui

Hi Guo, Yes, You can perform a schema modification, but pls be cautious in doing that. Schema errors can result is loss of complete domain or forest. I would recommend you to first perform the schema upgrade in test lab. Once you verified in test lab, perform system state backup before implementing schema modification in production environment. Once an attribute is created into schema, it can't be removed but can only be deactivated. Stop making unneeded Active Directory schema changes http://www.networkworld.com/community/node/24144 Best Practices for Active Directory Schema changes http://blog.chrislehr.com/2009/08/best-practices-on-schema-upgrades.htm Schema - What is the Best Practise for Updating ? http://blogs.technet.com/b/janelewis/archive/2009/05/12/schema-what-is-the-best-practise-for-updating.aspx http://blogs.technet.com/b/askpfeplat/archive/2012/05/28/best-practices-for-implementing-schema-updates-or-how-i-learned-to-stop-worrying-and-love-the-forest-recovery.aspx Previous Discussion: http://social.technet.microsoft.com/Forums/en/winserverDS/thread/c9a0086a-3e17-42bf-8bd0-25e18221fb38 Regards, Rafic If you found this post helpful, please give it a "Helpful" vote. If it answered your question, remember to mark it as an "Answer". This posting is provided "AS IS" with no warranties and confers no rights! Always test ANY suggestion in a test environment before implementing!