1. A system for providing a virtual desktop service, the system comprising: a host server configured to provide the virtual desktop service to a user's device using a virtual machine; a distributed file system configured to store data for the virtual machine; and a cache server configured to, when a request to process data reading is received from the virtual machine inside the host server, pre-read a data segment for the requested process of data reading from the distributed file system and store the pre-read data segment in a cache, and perform the process of data reading using the cache; wherein the cache server obtains information on the data segment from read distance maps each of which includes a plurality of blocks arranged in a predetermined format, each block corresponding to the data for the virtual machine and including information on a next block in the predetermined data segment to be read after a current block is read; and wherein each of the blocks provided in the read distance maps comprises: i) first information indicating reusability of each block, ii) second information indicating, when each block is a block constituting the data segment, whether the data segment is based on temporal locality or spatial locality, iii) third information indicating a value expressed as the data segment based on the spatial locality where the special locality represents the offset value to the next block read, and iv) fourth information indicating a value expressed as the data segment based on the temporal locality.