Storage device and storage management method
To provide a storage device by which distribution of data to an added memory device may be carried out in a short period of time. In a case where any new SSD is added to the storage device, a storage controller carries out first data distribution processing moving any piece of user data in a parity group from existing SSDs to the added SSD and second data distribution processing increasing the number of pieces of the user data configuring the parity group from a first number to a second number after the first data distribution processing and storing the user data in a plurality of memory devices SSDs.
1. A storage device comprising a control unit and a plurality of memory devices, wherein
a parity group is defined by a first configuration including a first number of pieces of user data and redundant data generated from the first number of pieces of the user data,
the user data and the redundant data in the parity group are stored in the different memory devices from each other,
in a case where any new memory device is added to the storage device, the control unit carries out
first data distribution processing moving any piece of the user data in the parity group from the existing memory devices to the added memory device, and
second data distribution processing increasing the number of pieces of the user data which define the first configuration of the parity group from the first number to a resultant second number, wherein the presence of the second number of pieces of the user data define a second configuration, after the first data distribution processing, and storing the resultant user data in the plurality of memory devices, and
when the control unit calculates a life difference resulting from subtraction of a remaining life of existing devices that are the existing memory devices from a remaining life of an added device that is the added memory device and receives a write request for data,
if the life difference is equal to or greater than the threshold, the control unit distributes and stores the data, by a first data unit, among and in same number of memory devices as the number of the existing devices selected from the existing devices and the added device, and
if the life difference is smaller than the threshold, the control unit newly distributes and stores the data, by a second data unit greater than the first data unit, among and in larger number of the existing devices and the added device than the number of the existing devices.
2. The storage device according to claim 1 , wherein
the lives of the existing and added memory devices are based on amounts of writing, and
the control unit determines a moved data volume for movement from each of the existing memory devices to the added memory device, based on the life of the existing memory device, in the first data distribution processing.
3. The storage device according to claim 2 , wherein
the control unit determines timing of start of the second data distribution processing, based on the life difference among the memory devices.
4. The storage device according to claim 1 , wherein
a data volume of the redundant data with respect to the user data is decreased in the second data distribution processing.
5. The storage device according to claim 1 , wherein
the data is stored in a log structure scheme, and
in the second data distribution processing, the control unit does not change the number of pieces of the data in the parity group that is stored before starting the second data distribution processing but changes the number of pieces of the data in the parity group, the number of pieces of the data being stored after starting the second data distribution processing, to the second number.
6. A storage management method executed by a storage device including a plurality of memory devices,
a parity group being defined by a first configuration including a first number of pieces of user data and redundant data generated from the first number of pieces of the user data,
the user data and the redundant data in the parity group being stored in the different memory devices from each other,
in a case where any new memory device being added to the storage device, the method comprising:
first data distribution processing moving any piece of the user data in the parity group from the existing memory devices to the added memory device, and
second data distribution processing increasing the number of pieces of the user data which define the first configuration of the parity group from the first number to a resultant second number, wherein the presence of the second number of pieces of the user data define a second configuration after the first data distribution processing, and storing the resultant user data in the plurality of memory devices, and
when the control unit calculates a life difference resulting from subtraction of a remaining life of existing devices that are the existing memory devices from a remaining life of an added device that is the added memory device and receives a write request for data,
if the life difference is equal to or greater than the threshold, the control unit distributes and stores the data, by a first data unit, among and in same number of memory devices as the number of the existing devices selected from the existing devices and the added device, and
if the life difference is smaller than the threshold, the control unit newly distributes and stores the data, by a second data unit greater than the first data unit, among and in larger number of the existing devices and the added device than the number of the existing devices.