One technique for overcoming external fragmentation is the os shifts the partitions so that they are contiguous and so that all of the free memory is together in one block. however, the significant overhead makes it largely unsuitable for use in real-time systems

Compaction

Explanation: External fragmentation is the condition in which occurs in the disk storage or memory storage due to the creation of numerous vacant spaced holes. This process takes the available space or the allocation of the memory.

To stop this process , compaction method is used which shuffles the data of  memory so that all the free memory can be united to a single large unit .Relocation should occur in the dynamic nature so that the compaction can be successful process.

External fragmentation is the various free spaced holes that are generated in either your memory or disk space. External fragmented blocks are available for allocation, but may be too small to be of any use. ... When a page fault occurs for any page in memory, treat this as an access to the page.

answer; availability;