Memory system with first cache for storing uncompressed look-up table segments and second cache for storing compressed look-up table segments

A memory system connectable to a host, comprising:

• a nonvolatile first memory;
• a second memory in which a plurality of look-up table segments are stored, each of the look-up table segments containing information that correlates logical addresses indicating locations in a logical address space of the memory system with physical addresses indicating locations in the first memory;
• a volatile third memory including a first cache and a second cache;
• a compressor configured to perform compression on look-up table segments supplied thereto;
• and
• a memory controller configured to:
• store first look-up table segments in the first cache and second look-up table segments in the second cache,
• determine a frequency of sequential writes based on a plurality of write commands from the host, and
• automatically adjust a ratio between a first capacity, which is a capacity of the first cache, and a second capacity, which is a capacity of the second cache, according to the frequency of sequential writes,
• wherein the first look-up table segments in the first cache are stored in non-compressed form, and the second look-up table segments in the second cache are supplied to and compressed by the compressor before being stored in the second cache, and
• wherein the memory controller increases the first capacity when the frequency of sequential writes is smaller than or equal to a first value and increases the second capacity when the frequency of sequential writes is greater than or equal to a second value, the first value being less than the second value.