A data collation method performed by a storage controller in a storage array, wherein the storage array comprises the storage controller and a storage device, wherein the method comprises: a.) adding a no-decompression flag to a first read instruction, and subsequently sending the first read instruction to the storage device, wherein the first read instruction carries a first logical address and the no-decompression flag, wherein the no-decompression flag is used to instruct the storage device not to decompress first data (S 201), wherein: ∘ the first data is stored in the storage device in an area pointed to by a first physical address of the storage device, ∘ the first logical address is mapped to the first physical address, ∘ a length of an area, pointed to by the first logical address is equal to a length of second data, ∘ a length of the area, in the storage device, pointed to by the first physical address is equal to a length of the first data, ∘ the first data is compressed data of the second data, and ∘ an address of the storage array is mapped to the first logical address; b.) receiving the first data sent by the storage device (S 204), c.) assigning a second logical address to the first data, d.) sending a write instruction to the storage device, wherein the write instruction carries the second logical address and the first data, and a length of an area pointed to by the second logical address is equal to the length of the first data (S 205), e.) establishing a mapping relationship between the address of the storage array and the second logical address (S 208), f.) sending a data erasure instruction to the storage device, wherein the data erasure instruction carries the first logical address and the data erase instruction is used to delete the first data and is used to delete a mapping relationship, stored in the storage device, between the first logical address and the first physical address. a.) adding a no-decompression flag to a first read instruction, and subsequently sending the first read instruction to the storage device, wherein the first read instruction carries a first logical address and the no-decompression flag, wherein the no-decompression flag is used to instruct the storage device not to decompress first data (S 201), wherein: ∘ the first data is stored in the storage device in an area pointed to by a first physical address of the storage device, ∘ the first logical address is mapped to the first physical address, ∘ a length of an area, pointed to by the first logical address is equal to a length of second data, ∘ a length of the area, in the storage device, pointed to by the first physical address is equal to a length of the first data, ∘ the first data is compressed data of the second data, and ∘ an address of the storage array is mapped to the first logical address; ∘ the first data is stored in the storage device in an area pointed to by a first physical address of the storage device, ∘ the first logical address is mapped to the first physical address, ∘ a length of an area, pointed to by the first logical address is equal to a length of second data, ∘ a length of the area, in the storage device, pointed to by the first physical address is equal to a length of the first data, ∘ the first data is compressed data of the second data, and ∘ an address of the storage array is mapped to the first logical address; b.) receiving the first data sent by the storage device (S 204), c.) assigning a second logical address to the first data, d.) sending a write instruction to the storage device, wherein the write instruction carries the second logical address and the first data, and a length of an area pointed to by the second logical address is equal to the length of the first data (S 205), e.) establishing a mapping relationship between the address of the storage array and the second logical address (S 208), f.) sending a data erasure instruction to the storage device, wherein the data erasure instruction carries the first logical address and the data erase instruction is used to delete the first data and is used to delete a mapping relationship, stored in the storage device, between the first logical address and the first physical address.