This paper gives an overview of the different works in literature that consider virtual machine migration. The different works related to virtual migration are classified into different categories. Some of the works that consider less explored areas of virtual machine migration are discussed in detail. improved time-series based precopy approach technique is proposed. With the time-series prediction technique, frequently updated dirty pages (high dirty pages) are identified more precisely, and transmit them in the last round of iteration, in order to reduce unnecessary, repeated transmission of dirty pages. transferring huge number of unnecessary memory pages
resulting into increase in the total migration time and downtime. Memory Compression, a faster migration technique, is the second step of a combined approach. Various compression methods named RLE, Huffman Coding, MEMCOM, WKdm and LZ are classified. Proposed approach of modifying optimized pre-copy will reduce unnecessary transfer of pages and its combination with Characteristic Based Compression (CBC) algorithm will handle two factors viz. (i) total migration time and (ii) total downtime and make migration process more effective.