According to one embodiment, a memory system is configured to operate as one of semiconductor storage devices in a storage array. The memory system includes a nonvolatile memory and a controller. The controller executes a write operation of writing data, received from a host, to the nonvolatile memory. The controller receives, from the host or another semiconductor storage device in the storage array, a notification indicative of a value related to an amount of reduction in write performance of the another semiconductor device. The controller reduces performance of the write operation based on the value notified by the received notification.