Storage device supporting trim operation and storage system including the same

A storage system comprising:

• a storage device comprising a plurality of nonvolatile memory cells;
• and
• a host configured to send a reference valid ratio to the storage device,
• wherein the storage device is configured to perform an internal trim operation on data stored based on a least recently used (LRU) scheme in response to the reference valid ratio of the storage device being higher than or equal to the valid data ratio, and send information, indicating that target data of the internal trim operation has been deleted, to the host.

A method of operating a storage device including a plurality of nonvolatile memory cells, the method comprising:

• setting a reference valid ratio;
• sorting pieces of valid data, among pieces of data stored in the storage device, based on a data access point in time;
• performing an internal trim operation on cold data being data accessed less recently than a threshold recency, among the pieces of data stored in the storage device, in response to a valid data ratio of the storage device being higher than or equal to the reference valid ratio;
• and
• sending internal deletion information, indicating the cold data has been deleted, to a host.