Memory system and operating method thereof

1. A memory system comprising:

a memory device;

a write buffer suitable for buffering a first host data and a second host data;

a chip-kill cache suitable for caching one among a first chip-kill parity candidate and a second chip-kill parity candidate for the first host data and the second host data, respectively;

a chip-kill buffer suitable for buffering the first chip-kill parity candidate when the first chip-kill parity candidate cached in the chip-kill cache is evicted from the chip-kill cache;

a chip-kill manager suitable for generating a first chip-kill parity by performing an XOR operation on the first host data and the first chip-kill parity candidate and generating a second chip-kill parity by performing an XOR operation on the second host data and the second chip-kill parity candidate; and

a processor suitable for controlling the memory device to program the first host data and the first chip-kill parity into a first open block, and to program the second host data and the second chip-kill parity into a second open block,

wherein the chip-kill buffer has a larger capacity than the chip-kill cache, and

wherein, when the first chip-kill parity candidate is a cache hit in the chip-kill cache, the processor controls the chip-kill manager to read the first chip-kill parity candidate from the chip-kill cache and update the read first chip-kill parity candidate, and when the first chip-kill parity candidate is a cache miss in the chip-kill cache, the processor controls the chip-kill manager to read the first chip-kill parity candidate from the chip-kill buffer and update the read first chip-kill parity candidate.

2. The memory system of claim 1 , wherein, when a size of the first host data buffered in the write buffer reaches a set write stripe unit, the processor controls the memory device to program the first host data in the first open block.

3. The memory system of claim 2 , wherein the write stripe unit is a sum of sizes of pages that are located at the same index of a super memory block.

4. The memory system of claim 2 , wherein the processor determines whether the first host data is a cache hit or a cache miss, while a program operation is performed on the first open block, and

the cache hit includes a case that the first chip-kill parity candidate is cached in the chip-kill cache.

5. The memory system of claim 4 , wherein the cache miss includes a case that the second chip-kill parity candidate is cached in the chip-kill cache.

6. The memory system of claim 5 , wherein, when the cached second chip-kill parity candidate is dirty and there is no remaining space in the chip-kill cache, the processor evicts the second chip-kill parity candidate from the chip-kill cache and writes the evicted second chip-kill parity candidate into the chip-kill buffer.

7. The memory system of claim 5 , wherein, when the cached second chip-kill parity candidate is clean, the processor deletes the second chip-kill parity candidate from the chip-kill cache.

8. The memory system of claim 2 , wherein, when the first host data includes a first piece of data and a second piece of data and the first piece of data includes a start piece of data for the first open block,

the processor controls the chip-kill manager to cache the first piece of data in the chip-kill cache and to cache the first chip-kill parity candidate which is generated by performing an XOR operation on the first piece of data and the second piece of data in the chip-kill cache.

9. The memory system of claim 8 , wherein, when the second piece of data includes a last piece of data,

the processor controls the memory device to program the first chip-kill parity which is generated by performing an XOR operation on the first chip-kill parity candidate and the second piece of data that are cached in the chip-kill cache into the first open block.

10. The memory system of claim 9 , wherein the start piece of data is programmed into a first page of the first open block, and

the last piece of data is programmed into the last page of the first open block except for the first chip-kill parity.

11. A method for operating a memory system, the method comprising:

buffering a first host data and a second host data in a write buffer;

caching one among a first chip-kill parity candidate and a second chip-kill parity candidate for the first host data and the second host data in a chip-kill cache, respectively;

buffering the first chip-kill parity candidate into a chip-kill buffer when the first chip-kill parity candidate cached in the chip-kill cache is evicted from the chip-kill cache;

generating a first chip-kill parity by performing an XOR operation on the first host data and the first chip-kill parity candidate and generating a second chip-kill parity by performing an XOR operation on the second host data and the second chip-kill parity candidate; and

programming the first host data and the first chip-kill parity into a first open block and programming the second host data and the second chip-kill parity into a second open block,

wherein, when the first chip-kill parity candidate is a cache hit in the chip-kill cache, the first chip-kill parity candidate from the chip-kill cache is read and updated, and when the first chip-kill parity candidate is a cache miss in the chip-kill cache, the first chip-kill parity candidate from the chip-kill buffer is read and updated, the chip-kill buffer having a larger capacity than the chip-kill cache.

12. The method of claim 11 , further comprising:

when a size of the first host data buffered in the write buffer reaches a set write stripe unit, programming the first host data in the first open block.

13. The method of claim 12 , wherein the write stripe unit is a sum of sizes of pages that are located at the same index of a super memory block.

14. The method of claim 12 , wherein the cache hit includes a case that the first chip-kill parity candidate is cached in the chip-kill cache.

15. The method of claim 12 , wherein the cache miss includes a case that the second chip-kill parity candidate is cached in the chip-kill cache.

16. The method of claim 15 , further comprising:

when the cached second chip-kill parity candidate is dirty and there is no remaining space in the chip-kill cache, evicting the second chip-kill parity candidate from the chip-kill cache and writing the evicted second chip-kill parity candidate into the chip-kill buffer.

17. The method of claim 15 , further comprising:

when the cached second chip-kill parity candidate is clean, deleting the second chip-kill parity candidate from the chip-kill cache.

18. The method of claim 12 , further comprising:

when the first host data includes a first piece of data and a second piece of data and the first piece of data includes a start piece of data for the first open block, caching the first piece of data in the chip-kill cache and caching the first chip-kill parity candidate which is generated by performing an XOR operation on the first piece of data and the second piece of data in the chip-kill cache.

19. The method of claim 18 , further comprising:

when the second piece of data includes a last piece of data, programming the first chip-kill parity which is generated by performing an XOR operation on the first chip-kill parity candidate and the second piece of data that are cached in the chip-kill cache into the first open block.

20. The method of claim 19 , wherein the start piece of data is programmed into a first page of the first open block, and

the last piece of data is programmed into the last page of the first open block except for the first chip-kill parity.