How to Size Page File

Captain Jack

Extraordinary Member
What is Page File:

In storage, a pagefile is a reserved portion of a hard disk that is used as an extension of random access memory (RAM) for data in RAM that hasn’t been used recently. A pagefile can be read from the hard disk as one contiguous chunk of data and thus faster than re-reading data from many different original locations.
RAM is a limited resource, whereas virtual memory is, for most practical purposes, unlimited. There can be many processes, each one having its own 2 GB of private virtual address space. When the memory that is in use by all the existing processes exceeds the amount of available RAM, the operating system moves pages (4 KB pieces) of one or more virtual address spaces to the hard disk, thus freeing that RAM frame for other uses. In Windows systems, these “paged out” pages are stored in one or more files that are named pagefile.sys in the root of a partition. There can be one such file in each disk partition

Note: To understand this post better we need Process Explorer by SysInternals

Address Space Limits

  • One virtual memory limit is address space
  • Another is the system commit limit
The address space for 32-Bit Computers are
32-bits = 2^32 = 4 GB
Where by default 2GB is User Process space and 2GB is System Space. With boot.ini: /3GB or /USERVA the User Process space can be 3GB and 1GB of System space. So 32-Bit can run out of the address space. Only way to increase the address space to upgrade to 64-Bit
The address space for 32-Bit Computers are
64-bits = 2^64 = 17,179,869,184 GB

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