Garbage collection for data storage

A system comprising:

• data processing hardware of one or more server computers;
• and
• memory hardware in communication with the data processing hardware, the memory hardware storing instructions that when executed on the data processing hardware cause the one or more server computers to perform operations comprising:
• receiving, from a user of a user device in communication with the one or more server computers:
• a cost threshold representing a benefit of reclaiming storage space associated with each data object of a plurality of data objects associated with the user;
• and
• a policy rule,
• determining a threshold storage cost based on:
• the cost threshold;
• and
• an access window associated with each of the data objects of the plurality of data objects associated with the user, the access window having an expiration date in the future;
• determining a future storage cost associated with a given data object of the plurality of data objects associated with the user;
• determining whether the future storage cost associated with the given data object satisfies the threshold storage cost,
• determining whether the policy rule applies to the given data object;
• and
• after the expiration date of the access window of the given data object has expired and when the future storage cost associated with the given data object satisfies the threshold storage cost:
• when the policy rule does not apply to the given data object, automatically deleting the given data object;
• and
• when the policy rule does apply to the give data object, retaining the given data object.