Storage device and operating method of storage device

1. A storage device comprising:

a nonvolatile memory device;

a dynamic random access memory including a first region and a second region including a set of segments; and

a controller configured to,

use the first region as a device memory;

use the second region of the dynamic random access memory to store data for a modification during a first time;

use the second region as a journal memory to store a journal indicating the modification during second time,

expose a user region of the nonvolatile memory device to an external host device as a first access region of a block unit,

select a first segment of the segments, to select at least two second segments from the remaining segments of the segments other than the first segment, and

provide non volatility to the selected segments,

wherein the at least two second segments are dynamically changed in a ring buffer manner within the remaining segments, and

wherein the modification is for data of the user region.

2. The storage device of claim 1 , wherein the controller is further configured to,

back up data stored in the selected segments to the nonvolatile memory device based on an interruption of power from the external host device, and

load the data onto the selected segments based on a restoration of power from the external host device.

3. The storage device of claim 1 , wherein the controller is further configured to,

provide the first segment as a storage space of a superblock of a journal region of the external host device, and

provide the at least two second segments as a storage space of at least one transaction of the journal region of the external host device.

4. The storage device of claim 1 , wherein the controller is further configured to expose the second region to the external host device as both a second access region of the block unit and a third access region of a byte unit.

5. An operating method of a storage device including a controller, a nonvolatile memory device, and a dynamic random access memory, the method comprising:

providing, by the controller, a portion of a storage space of the nonvolatile memory device to an external host device as a user region; and

providing, by the controller, a portion of a storage space of the dynamic random access memory to the external host device as a journal region, a write operation of a byte unit and a read operation of a block unit being permitted, the journal region including segments, and

providing, by the controller, nonvolatility to a first segment and at least two second segments from among the segments, the first segment being fixed and the at least two second segments being dynamically changed.