Storage device and operation method thereof

A storage device, comprising:

• a nonvolatile memory device;
• a buffer memory device comprising a write cache region and an internal traffic region;
• a storage controller configured to control the nonvolatile memory device and the buffer memory device;
• and
• a memory interface circuit configured to communicate with the nonvolatile memory device,
• wherein the storage controller is further configured to:
• fetch, from an external host device using a host interface circuit, a write command and write data;
• perform a maintenance operation on the nonvolatile memory device;
• detect a write cache level of the write cache region;
• perform, through the memory interface circuit, write cache processing for the write cache region;
• perform, through the memory interface circuit, internal traffic processing for the internal traffic region;
• and
• control a cache processing rate of the write cache processing, based on the write cache level,
• wherein the write cache region is configured to store the write data, and
• wherein the internal traffic region is configured to store data to be used by the maintenance operation.

An operating method of a storage device, the operating method comprising:

• detecting a write cache level of a buffer memory device of the storage device;
• and
• controlling a nonvolatile memory device of the storage device in at least one of a normal mode, a first urgent mode, or a second urgent mode, based on the write cache level,
• wherein at least one of a cache processing rate or a fetch rate is differently determined in the normal mode, the first urgent mode, and the second urgent mode,
• wherein the cache processing rate indicates a rate at which write data stored in the buffer memory device is flushed to the nonvolatile memory device, and
• wherein the fetch rate indicates a rate at which a write command and write data are fetched from an external host device.