Each User My site is made of 2 site collection: the My Site host site collection and the user's individual site collection.
The My Site host site collection is a special site collection that hosts My Newsfeed and My Profile sections of all users' My Sites. A user's individual site collection hosts the My Content section of his or her individual My Site.
While creating User Profile Service Application, we provide a web application which will host all user profile. The DB of this web application stored My Content of all users. We can add additional DB for this web application
When user click on My Content the user’s individual site collection gets created.Below are the things you need to have in place to create individual site collection.
Wildcard inclusion of managed path such as sites or personal.
Self Service Site creation is enabled
Users should have created personal site permission.
My Sites require that a site collection exists at the Web application root (which appears as / in the user interface). Without this, you will receive a message that indicates that there is no site collection at the root when you try to enable self-service site creation for the Web application.
The self-service site creation feature has special security considerations for cross-site scripting. This strengthens the recommendation to host My Sites in a dedicated Web application to isolate any scripts running in a My Site from affecting other sites in your environment.
The Trusted My Site Host Locations feature prevents a user from creating more than one My Site in an organization with multiple User Profile service applications. For example, in a server farm deployment that spans geographic regions, you may have separate User Profile service applications for each region. By default, a user can create a My Site in each User Profile service application, which could cause unwanted results from both an administration perspective and a user perspective. To prevent individual users from creating multiple MySites, configure trusted My Site host locations. When this feature is configured, users are redirected to the single My Site host location that is intended for their accounts regardless of where they are located . This feature ensures that each user can create only one My Site in an organization.
When you have multiple My Site farms (User Profile service applications), you have to configure trusted My Site host locations and potentially use the User Profile Replication Engine to keep data synchronized among the User Profile service applications.
Storage Requirement: People can upload lot of documents in my site. So it’s important to have a quota defined on the storage. The Personal Site quota template is automatically applied when each user creates an individual site collection in his or her My Site by clicking the My Content tab. By default, this quota template has a storage limit of 100 MB. You should configure the quota template before you deploy My Sites in your enterprise because subsequent changes will not affect existing site collections. If you decide to configure the quota template later, you can use Windows PowerShell to script an update for existing site collections
You can restrict the file types that users put in their MySites by using the “Blocked file type” option in CA.
User Profile Service Application creates 3 databases:
Profile database – used to store user profile information.
Synchronization database – used to store configuration and staging information for synchronizing profile data from external sources such as the Active Directory Domain Services (AD DS).
Social tagging database – used to store social tags and notes created by users. Each social tag and note is associated with a profile ID.
If you decide to disable My Sites completely, you can still get the benefits of People Search. You can configure permissions so that users can update their profiles without enabling them to create a My Site (Disable Self Service site creation). This enables you to block the creation of site collections in My Sites, but still enables users to access their own profile information and to search for and view the profiles of other users.