Because sharks get their teeth cleamed by fish in the sea weed
If a paging file resides on a partition that contains other data, it may experience fragmentation as it expands to satisfy the extra virtual memory that is required.
In order to prevent page file fragmentation.
external fragmentation use in paging
Fragmentation
From TechNet: Set the Same Initial and Maximum Size Setting the paging file's initial size and maximum size to the same value increases efficiency because the operating system does not need to expand the file during processing. Setting different values for initial and maximum size can contribute to disk fragmentation.
By paging I am assuming you mean the page file which cannot be defragmented whilst you are running windows. therefore you need a defragmenter that perfomes an offline defrag. I assume too that is what you meant by external fragmentation. Companies like RAXCO, offer an offline defragmenter which does solve your problem assuming I have understood it correctly.
If there are large blank spaces in each page of the program then internal fragmentation can occur. Smaller pages can remedy this, but the overall amount of pages will then increase, causing slowed execution.
Paging file is located in the root folder of the system drive.
if you remove the paging file from the boot partition, Windows cannot create a dump file (Memory.dmp) in which to write debugging information in the event that a kernel mode Stop Error message occurs. This could lead to extended downtime if you must debug to troubleshoot the Stop error message.
Paging File
The "paging file" is already a form of virtual memory. There is no way to use a paging file in the same way as you would normal RAM, as hard drives are hundreds of times slower than RAM.
Paging is solution to external fragmentation problem whichis to permit the logical address space of a process to benoncontiguous, thus allowing a process to be allocatingphysical memory wherever the latter is available.