An identity column in SqlServer2012 has an attribute:
When the server restarts, the identity column defined as int automatically adds 1000 to the original maximum value. For example, your original self-increment column of the maximum value is 2, then you restart after inserting a piece of data into the table, your self-increment column will be 1002, in 2008 should be 3.
The identity column defined as bigint automatically adds 10000 to the original maximum value. For example, your original self-increment column of the maximum value is 2, then you restart after inserting a piece of data into the table, your self-increment column will be 10002, in 2008 should be 3.
For details, please see the following links:
Http://www.codeproject.com/Tips/668042/SQL-Server-Auto-Identity-Column-Value-Jump-Is
Identity column Auto-grow issue (SQL Server, identity, column Value jump Issue)