RAID storage device, host, and RAID system

A host device connected to nonvolatile memory devices including first memory devices configured to store at least one of data chunks and corresponding parity, and a second memory device configured to serve as a spare memory region, the host device comprising:

• a host internal memory configured to store a count table indicating used regions of each of the first memory devices;
• and
• a host processing unit configured to control a redundant array of independent disks (RAID) operation on the first memory devices and update the count table in response to the RAID operation, and further configured to control a rebuild operation on a failed first memory device among the first memory devices using the second memory device based on the count table,
• wherein the host processing unit generates a hash value by performing hash modulation based on a logical block address at which the at least one of the data chunks and the corresponding parity are stored in non-failed first memory devices of the first memory devices, and stores in a plurality of buckets of the count table counts corresponding to a number of times the hash modulation is performed on the logical block address.

A redundant array of independent disks (RAID) system comprising:

• a host and solid state drives connected to the host,
• wherein each one of the solid state drives comprises
• first memory devices configured as a RAID and further configured to store at least one of data and corresponding parity,
• a second memory device configured to serve as a spare memory device, and
• a memory controller configured to perform data access operations on the first memory devices and the second memory device,
• the RAID system storing a count table indicating used regions for each of the first memory devices, and
• upon identifying a failed first memory device from among the first memory devices, the RAID system accesses the at least one of the data and the corresponding parity in only used regions of non-failed first memory devices from among the first memory devices by referencing the count table to perform a rebuild operation on the failed first device using the second memory device,
• wherein the count table includes buckets indicating positional information for the used regions and unused regions for each of the first memory devices and the second memory device, and
• wherein the RAID system generates a hash value by performing hash modulation based on a logical block address of a used region for each of the non-failed first memory devices, and stores in respective buckets of the count table counts corresponding to a number of times the hash modulation is performed on the logical block address.