Disk array device, control method for disk array device, and control program for disk array device

A control method for a disk array

• including a plurality of solid state drives (SSDs) including an active SSD pool comprising a first set of the SSDs that are available as write destinations and a standby SSD pool comprising a remainder of the SSDs that are not available as write destinations, the control method comprising:
• receiving from a host a plurality of first write instructions that each include respective write data to be written to the active SSD pool and, for each first write instruction:
• for each SSD belonging to the active SSD pool, converting the respective first write instruction to a respective second write instruction and provide the respective second write instruction to the respective SSD, the respective second write instruction including the respective write data and a respective start physical address at which the write data is to be stored in the respective SSD,
• wherein each SSD in the active SSD pool is configured to, for each first write instruction:
• receive the respective second write instruction;
• determine a respective start internal address corresponding to the respective start physical address;
• and
• write the respective write data beginning at the respective start internal address and ending at a respective actual end internal address,
• wherein the control method further comprises, for each first write instruction and for each SSD in the active SSD pool:
• deriving a respective expected end internal address corresponding to the respective actual end internal address at which writing of the respective write data ended;
• detecting that there is a discontinuity between the respective expected end internal address and the respective actual end internal address;
• in response to detecting the discontinuity, incrementing a respective discontinuity count for the respective SSD,
• wherein for a first SSD belonging to the active SSD pool, the respective discontinuity count exceeds a predetermined upper limit value,
• and wherein the control method further comprises, in response to the respective discontinuity count relating to the first SSD belonging to the active SSD pool exceeding the predetermined upper limit value:
• indicating an allowable decrease in write capacity in the first SSD;
• copying the write data stored on the first SSD to a region of continuous write destination addresses in a second SSD belonging to the standby SSD pool;
• removing the first SSD from the active SSD pool;
• and
• adding the second SSD to the active SSD pool.

A non-transitory storage medium storing a control program for a disk array device,

• including a plurality of solid state drives (SSDs) including an active SSD pool comprising a first set of the SSDs that are available as write destinations and a standby SSD pool comprising a remainder of the SSDs that are not available as write destinations, the control program executable by the disk array device to perform processing comprising:
• receiving from a host a plurality of first write instructions that each include respective write data to be written to the active SSD pool and, for each first write instruction:
• for each SSD belonging to the active SSD pool, converting the respective first write instruction to a respective second write instruction and provide the respective second write instruction to the respective SSD, the respective second write instruction including the respective write data and a respective start physical address at which the write data is to be stored in the respective SSD,
• wherein each SSD in the active SSD pool is configured to, for each first write instruction:
• receive the respective second write instruction;
• determine a respective start internal address corresponding to the respective start physical address;
• and
• write the respective write data beginning at the respective start internal address and ending at a respective actual end internal address,
• wherein the processing further comprises, for each first write instruction and for each SSD in the active SSD pool:
• deriving a respective expected end internal address corresponding to the respective actual end internal address at which writing of the respective write data ended;
• detecting whether there is a discontinuity between the respective expected end internal address and the respective actual end internal address;
• and
• in response to detecting the discontinuity, increment a respective discontinuity count for the respective SSD,
• and wherein the processing further comprises, when the respective discontinuity count relating to a first SSD belonging to the active SSD pool exceeds a predetermined upper limit value:
• indicating an allowable decrease in write capacity in the first SSD;
• copying the write data stored on the first SSD to a region of continuous write destination addresses in a second SSD belonging to the standby SSD pool;
• removing the first SSD from the active SSD pool;
• and
• adding the second SSD to the active SSD pool.