If only certain subsites need to be archived within a SharePoint organization, perform the following:

1. Install the SharePoint components of Enterprise Vault (EV) on the SharePoint server.
2. Configure the SharePoint server in Targets.
3. Configure the Collection Site and set it to 'Do not Archive Subsites'
4. Add the Subsite(s) within the Collection Site that need to be archived and set them to 'Archive this Subsite' in the properties of the Subsites.
5. If archiving of a Subsite is no longer needed, just uncheck the 'Archive this Subsite' option.

In some versions of EV (up to Version 7 Sp2) when you right-click on a subsite, there will be a 'run now' option. This is not a valid option and has been removed in future releases.
If the 'run now' option is selected from the properties tab of the subsite, it will return the error message: 'Parent SharePoint server is not enabled on archiving.'