Constraining the file system cache on 64-bit Windows

Technote (troubleshooting)


Problem

The file system cache on 64-bit versions of Windows will, by default, attempt to use the majority of system memory, and may thus cause issues for applications running on the platform. This is due in part to the fact that the "default" setting for the file system cache moved from 1GB on 32-bit Windows to 1TB on 64-bit Windows.

Resolving the problem

The file system cache on 64-bit versions of Windows will, by default, attempt to use the majority of system memory, and may thus cause issues for applications running on the platform. This is due in part to the fact that the "default" setting for the file system cache moved from 1GB on 32-bit Windows to 1TB on 64-bit Windows.
To address this issue (as well as possible for an application), Lotus has implemented code within Domino which calls the Microsoft API SetSystemFileCacheSize(), in order to set a maximum size. By default, Domino will set this maximum size to 30% of the physical memory on the system. A user can change this setting by setting the notes.ini variable MEM_FSCachePercentMem to a percent number, to indicate the percent of memory.

For example, setting MEM_FSCachePercentMem=40 in the notes.ini will cause Domino to set the maximum file system cache size to 40% of the physical memory on the system. Note that the lowest number presently supported is 10%, and the highest number is 95%; numbers outside these limits will be set to the default of 30%.

Key notes

  1. This setting is system-wide and affects all processes on the system, as it affects the file system cache for the machine.
  2. Domino sets the maximum file cache size automatically. No additional configuration is required to adjust for the amount of available physical memory.
  3. This setting must be set identically within each Domino partition on a system. Since it is a global setting, if one partition is 70 and another 30, then the setting of one will get overridden by the other when the second partition is launched.
  4. This is not an optimal solution as it requires the user to "determine" the best value for the file system cache for their system/load, however, it is the only solution which is presently supported by Microsoft. IBM is actively working with Microsoft to see if a "better" solution can be found to this issue.
  5. In order to make this change in the file system cache setting, the user must have the SE_INCREASE_QUOTA_NAME privilege, otherwise the setting of the cache will fail.
  6. This API requires 64-bit Windows 2003/XP to be at SR2/SP2 or higher, otherwise the API will not be available. 64-bit Windows Vista and 64-bit Windows 2008 both have this API initially.

We now ship with Domino a tool called "cacheset.exe" which is used to affect these changes for 32 Bit Domino (64 Bit Domino calls the API directly), and which is available to see what the present system settings are for both 32- and 64-bit Domino. This binary is located in the same location as all of the Notes/Domino binaries. This is a 64-bit binary program (since the API requires 64-bit in order to set values greater than 4GB), and is thus invalid to run on 32-bit versions of Windows. On 64-bit Windows systems, running this application with no options (or incorrect flags, or -h, or -?) will result in a help/usage message printing to the command prompt.

Related information

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Document information


More support for:

IBM Domino

Software version:

8.0.2, 8.5

Operating system(s):

Windows 64bit

Reference #:

1377517

Modified date:

2009-03-09

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