hi,

Check this thread

http://www.symantec.com/connect/forums/upgrading-sep-ru6-mp2-sep-121

http://www.symantec.com/connect/forums/client-only-patch-sep-121-ru1-sep-ru6-mp2

Upgrading or migrating to Symantec Endpoint Protection 12.1.1000 (RU1)

http://www.symantec.com/business/support/index?page=content&id=TECH174545

Thanks for your post but all link are helpless.

HI,

You can follow Disaster receovery step and upgrade SEPM

Symantec Endpoint Protection 11.x: Best Practices for Disaster Recovery with the Symantec Endpoint Protection Manager

http://www.symantec.com/business/support/index?page=content&id=TECH102333

Symantec Endpoint Protection 12.1: Best Practices for Disaster Recovery with the Symantec Endpoint Protection Manager

http://www.symantec.com/business/support/index?page=content&id=TECH160736

http://www.symantec.com/connect/forums/question-about-migration-sep-11-sep-12

Ashish,

Why I follow disaster recovery procedure If am upgrading same server and needed only pre-requisites for SEP clients to upgrade smoothly.

Hi S2S,

I think you don't see Symatec Process

Upgrading or migrating to Symantec Endpoint Protection 12.1.1000 (RU1)

http://www.symantec.com/business/support/index?page=content&id=TECH174545

Overview of the migration process
Migration to the current version of Symantec Endpoint Protection includes the following steps in order:

• Create a migration plan
  Before you begin to install the Symantec Endpoint client, manager, and any administration upgrades, you should have a solid understanding of your network topology and a streamlined plan to maximize the protection of the resources on your network during the upgrade. Symantec strongly recommends that you migrate the entire network to the current version rather than managing multiple versions of Symantec Endpoint Protection.
• Backup up the database
  Before you upgrade, you should back up the database.
• Disable replication
  If your site uses replication, you must disable replication before upgrading Symantec Endpoint Protection Manager. You must disable replication at each site that replicates.
• Enable local authentication
  If Symantec Network Access Control is in use, then enable Local Authentication prior to migration.
• Disable "Protect client files and registry keys" Application Control Policy
  If the setting "Protect client files and registry keys" is used, disable it in the Application Control policy prior to the migration. WARNING: If this setting is not disabled, you may face issues at a later stage when migrating your clients. 
• Stop the Symantec Endpoint Protection Manager service
  Before you upgrade, you must manually stop the Symantec Endpoint Protection Manager service on every management server in your site. After you upgrade, the service is started automatically.
  WARNING: You must stop the Symantec Endpoint Protection Manager service before you upgrade, or you will corrupt your existing installation of Symantec Endpoint Protection Manager.
• Upgrade the Symantec Endpoint Protection Manager
  You do not need to uninstall management servers before you install the new version. The overinstall process saves legacy settings, and then upgrades to the latest version.
• Enabling replication after migration
  After you migrate all servers that used replication, including the servers that were configured for failover and load balancing, you must re-enable replication. After migration, you add a replication partner to enable replication. You only need to add replication partners on the computer on which you first installed the management server. Replication partners automatically appear on the other management servers.
• Upgrade the Symantec Endpoint Protection Clients
  You do not need to uninstall previous clients before you install the new version. The overinstall process saves legacy settings, and then upgrades to the latest version.

I think you not clear on my concern.. Am not asking anything relates to SEPM upgradation...

Hi,

Check user acoount control is disabled if not means the clients will not upgrade.

Thanks Srikant... Noted and anything else to consider.?

Nothing its fine u can upgrade go ahead...