A memory system characterized by comprising: a nonvolatile memory including a plurality of physical blocks; and a controller electrically connected to the nonvolatile memory, the controller configured to manage a plurality of namespaces (NS #1 to NS #n) for storing a plurality of kinds of data having different update frequencies, respectively, the plurality of namespaces (NS #1 to NS #n) including at least a first namespace for storing a first type of data, and a second namespace for storing a second type of data having a lower update frequency than the first type of data, wherein the controller is further characterized in that it is configured to receive a request from a host device specifying a first number of logical block addresses for the first namespace, a first number of physical blocks to be secured for the first namespace, and receive another request from a host device specifying a second number of logical block addresses for the second namespace, and a second number of physical blocks to be secured for the second namespace, allocate the first number of physical blocks as a physical resource for the first namespace, allocate the second number of physical blocks as a physical resource for the second namespace, allocate a remainder of capacity obtained when a capacity corresponding to the first number of logical block addresses is subtracted from a capacity corresponding to the first number of physical blocks as an over-provision area for the first namespace, wherein the over-provision area for the first namespace is not visible to the host device, and allocate a remainder of capacity obtained when a capacity corresponding to the second number of logical block addresses is subtracted from a capacity corresponding to the second number of physical blocks as an over-provision area for the second namespace, wherein the over-provision area for the second namespace is not visible to the host device. a nonvolatile memory including a plurality of physical blocks; and a controller electrically connected to the nonvolatile memory, the controller configured to manage a plurality of namespaces (NS #1 to NS #n) for storing a plurality of kinds of data having different update frequencies, respectively, the plurality of namespaces (NS #1 to NS #n) including at least a first namespace for storing a first type of data, and a second namespace for storing a second type of data having a lower update frequency than the first type of data, wherein the controller is further characterized in that it is configured to receive a request from a host device specifying a first number of logical block addresses for the first namespace, a first number of physical blocks to be secured for the first namespace, and receive another request from a host device specifying a second number of logical block addresses for the second namespace, and a second number of physical blocks to be secured for the second namespace, allocate the first number of physical blocks as a physical resource for the first namespace, allocate the second number of physical blocks as a physical resource for the second namespace, allocate a remainder of capacity obtained when a capacity corresponding to the first number of logical block addresses is subtracted from a capacity corresponding to the first number of physical blocks as an over-provision area for the first namespace, wherein the over-provision area for the first namespace is not visible to the host device, and allocate a remainder of capacity obtained when a capacity corresponding to the second number of logical block addresses is subtracted from a capacity corresponding to the second number of physical blocks as an over-provision area for the second namespace, wherein the over-provision area for the second namespace is not visible to the host device.