Greeting!
The reward for extraction indirectly incentivizes storage of data but does so only for popular and often requested data. To encourage long-term data storage, especially if data are rarely requested, some sort of data storage incentive is needed.
This piece on Ethereum Swarm describes the system of rewards for storage. Nodes enter into a data storage contract with the information owner for a period of time. The storage can be paid at the time of data storage (update) or after a certain period of time provided that the data is actually stored. In the event of a loss of data is detected during the duration of the contract, the node may be penalized, as each node requires an initial registration with a security deposit.
When you store data, the node returns a receipt that proves that it has accepted the file for storage. This receipt then allows you to check the storage situation of the associated data and, if necessary, to initiate a legal smart contract to penalize the offending node.
Since data is not static, a record with the same key can be rewritten several times. This means that not only can the original record correspond to the presented receipt, but a record with the same key that is newer to the timestamp can also correspond.
When the user initiates a data deletion operation, instead of physically deleting data, the data is replaced with a special "zero" record. The record can be physically deleted after expiration of its storage contract.
Best regards,
Ties community