Before you plan to import any mass data into your Salesforce organization, it is highly recommended that you take a backup of your existing data prior to the import. Salesforce.com provides a weekly Data Export Service, which exports all your data into the .csv files of 150 MB each and packs them into a .zip file of 512 MB. The number of files generated depends on the data in your organization. Data Export Service sends a link to the administrator via an e-mail where they can download the files from. Administrators can schedule the export every 29 days for the Professional Edition and every seven days for the Unlimited and Enterprise Editions.
Salesforce provides two ways to use the export services as follows: