Windows Server General Forum. Sign in to vote. Is there somewhat a formula to calculate Paging File size? For example, what should be the paging file size for a 8GB memory server?
Tuesday, July 6, AM. Hi Petarch, Normally, we set page file as 1. The Automatic memory dump feature initially selects a small paging file size. It would accommodate the kernel memory most of the time. If the system crashes again within four weeks, the Automatic memory dump feature sets the page file size as either the RAM size or 32 GB, whichever is smaller.
Kernel memory crash dumps require enough page file space or dedicated dump file space to accommodate the kernel mode side of virtual memory usage. If the system crashes again within four weeks of the previous crash, a Complete memory dump is selected at restart.
This requires a page file or dedicated dump file of at least the size of physical memory RAM plus 1 MB for header information plus MB for potential driver data to support all the potential data that is dumped from memory. Again, the system-managed page file will be increased to back this kind of crash dump.
If the system is configured to have a page file or a dedicated dump file of a specific size, make sure that the size is sufficient to back the crash dump setting that is listed in the table earlier in this section together with and the peak system commit charge.
Computers that are running Microsoft Windows or Microsoft Windows Server usually must have a page file to support a system crash dump. System administrators now have the option to create a dedicated dump file instead. A dedicated dump file is a page file that is not used for paging. Dedicated dump files can be put on any disk volume that can support a page file. We recommend that you use a dedicated dump file if you want a system crash dump but you do not want a page file.
To learn how to create it, see Overview of memory dump file options for Windows. By default, page files are system-managed. This means that the page files increase and decrease based on many factors, such as the amount of physical memory installed, the process of accommodating the system commit charge, and the process of accommodating a system crash dump. For example, when the system commit charge is more than 90 percent of the system commit limit, the page file is increased to back it.
This continues to occur until the page file reaches three times the size of physical memory or 4 GB, whichever is larger. This all assumes that the logical disk that is hosting the page file is large enough to accommodate the growth.
The following table lists the minimum and maximum page file sizes of system-managed page files in Windows 10 and Windows However, a page file or a dedicated dump file might still be required to back a system crash dump. Page files extend how much "committed memory" also known as "virtual memory" is used to store modified data. The system commit memory limit is the sum of physical memory and all page files combined.
It represents the maximum system-committed memory also known as the "system commit charge" that the system can support. The system commit charge is the total committed or "promised" memory of all committed virtual memory in the system. If the system commit charge reaches the system commit limit, the system and processes might not get committed memory.
This condition can cause freezing, crashing, and other malfunctions. Therefore, make sure that you set the system commit limit high enough to support the system commit charge during peak usage. System-managed page files automatically grow up to three times the physical memory or 4 GB whichever is larger, but no more than one-eighth of the volume size when the system commit charge reaches 90 percent of the system commit limit.
Using the information from the counters above and also examining the Peak Commit Charge number in Windows Task Manager shown below will give you an idea how much page file space would be needed if the system had to page out all private committed virtual memory. If the page file on the system is too large, the system does not use it any more or less. In other words, increasing the size of the page file unnecessarily does not change the system performance - it just means that the system has more nonshareable committed virtual memory.
If the page file is too small on the other hand, you may see error messages such as the "system is running low on virtual memory". Remember however, that you should also check whether there is a process that is leaking memory or a pool memory leak as those will also cause error messages relating to system resources and virtual memory to be displayed. So finally, a quick word on system-managed versus statically defined page files.
Some administrators will allow the system to manage the page file sizes. However, while this ensures that you are unlikely to encounter page file related resource depletion, it can lead to severe disk and page file fragmentation as the page file continuously shrinks and expands to keep up with the needs of the system.
If you are in a situation where there is severe disk fragmentation and you have a dynamic page file, I would strongly recommend reconfiguring the server with a static page file. You will also want to make sure that the disk is properly defragmented. To do this, you will need to schedule an appropriate maintenance window for your server.
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