The memory management algorithms in Windows 7 and Windows Server 2008 R2 operating systems were updated to address many file caching problems that were found in earlier versions of Windows. There are only certain unique situations in which you have to implement this service on computers that are running Windows 7 or Windows Server 2008 R2.
How to determine whether your system is affected
To determine whether your system is affected by this issue, install the SysInternals RamMap tool. You can obtain the tool from the following Windows Sysinternals website:
When you run the tool, select the
Use Counts option. This displays several columns that show the current pattern of memory usage. Click the
Active column to sort by the number of bytes used, and note the top usage directly under the total.
If the top use count is “Metafile,” and if a large part of available memory is being used, you are experiencing the System File Cache issue that is described in the "Symptoms" section. You can verify this by using Performance Monitor to monitor the
Memory\System Cache Resident Bytes counter and see the cache grow continuously over time.
Figure 1. Example RamMap output in which the computer is experiencing the issue.
Figure 2. Example RamMap output in which the computer is not experiencing the issue.
If the
Memory\System Cache Resident Bytes counter in Performance Monitor shows an upward trend over time, the computer is experiencing the issue, as shown in Figure 3.
Figure 3. Example Performance Monitor output in which the computer experiences the issue over time.
Restart requirements
You do not have to restart the computer when you install, uninstall, or use this service.
If you are you reading this article because you are working with a customer who believes that they are affected by this issue, follow these steps to help resolve the issue.
- Verify that the customer's RamMap output, perfmon, or poolmon data confirms that the System File Cache is consuming most of the physical RAM, as described earlier.
- To obtain the Windows Dynamic Cache Service, download it here.
- Some Dynamic Cache Registry settings are as follows:
File servers, you might want to try 1GB.
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DynCache\Parameters]
"MaxSystemCacheMBytes"=dword:00000400
"MinSystemCacheMBytes"=dword:00000064
"SampleIntervalSecs"=dword:0000003c
"CacheUpdateThresholdMBytes"=dword:00000064
Exchange 2007, you might want to try 500 MB:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DynCache\Parameters]
"MaxSystemCacheMBytes"=dword:000001F4
"MinSystemCacheMBytes"=dword:00000064
"SampleIntervalSecs"=dword:0000003c
"CacheUpdateThresholdMBytes"=dword:00000064
SQL 2005 and higher, in the past when working with SQL EE’s, have used 2GB:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DynCache\Parameters]
"MaxSystemCacheMBytes"=dword:000007D0
"MinSystemCacheMBytes"=dword:00000064
"SampleIntervalSecs"=dword:0000003c
"CacheUpdateThresholdMBytes"=dword:00000064