Configure the file system cache in Windows NT
The filesystem cache can work in two different modes:
- The default mode is that the filesystem cache only grows to a certain limit (8 MByte).
- The other mode is that the file system cache can grow until it has taken all memory (Up to 1 GByte depending on available memory).
To allow the file system cache to make use of "all" available memory:
- WinNT4: Open Control Panel -> Network -> Change properties for "Server" service to use "Maximize Throughput for File Sharing" (Will also change Server service memory usage).
- Win2k: Open Control Panel -> Network and Dial-up Connections -> Right-click Local Area Connection and select Properties -> Press Properties for service "File and Print Sharing for Microsoft Networks" to set "Maximize Data Throughput for File Sharing" (Will also change Server service memory usage)..
- WinXP/Win2k3: Open Control Panel -> System-Applet -> Advanced-Tab -> Performance-Settings-Button -> Advanced-Tab and select "System Cache"-Option.
[HKEY_LOCAL_MACHINE \System \CurrentControlSet \Control \Session Manager \Memory Management]
LargeSystemCache=1 (Default Srv. = 1, Default Prof. = 0)
- Microsoft Windows Dynamic Cache Service - Microsoft have recognized that 64bit versions of Windows has problems controlling the size if the working set for the file system cache (Up to 1 TB). This service can control the size of the file system cache according to workload, which can be useful if not using Windows 7 that tries to fix this issue. More Info NTDebugging
- SetCache - Sets a permanent upper limit for the file cache using the SetSystemFileCacheSize API (Win2k3/Win2k8/Vista only). Use a trigger to activate this tool to set file cache limits at startup.
- SysInternals CacheSet - It can only reset the cache to a certain size from where it can grow or shrink again.
- Uwe Sieber - NtCacheSet - Periodically resets the cache working set, just like CacheSet but does it with a specified interval.
- Uwe Sieber - SetSystemFileCacheSize - Sets a permanent upper limit for the file cache using the SetSystemFileCacheSize API (Win2k3/Win2k8/Vista only). Use a trigger to activate this tool to set file cache limits at startup.
Note the LargeSystemCache is allocated from kernel memory area, which is shared with the pagedpoolsize and systempages. So when limiting these from using max size, then it will allow the filesystem cache to reach its max size of 960 MByte (WinNT4 512 MByte), else it will be limited to 512 MByte.
[HKEY_LOCAL_MACHINE \System \CurrentControlSet \Control \SessionManager \MemoryManagement]
SystemCacheDirtyPageThreshold = 100 (MByte; Default = 0; 0 = Half of physical memory)
More Info MS KB 920739 (Doesn't limit the size of the read cache)
Note not all applications will benefit from a large system cache. Many disk intensive applications (Like database systems) includes their own cache manager, and doesn't make use of the operating system controlled file cache. For MS SQL and Exhange the optimal value is to disable the large system cache.
Note enabling the large system cache can give stability issues, because it will configure the kernel area to allocate max memory for the file cache, while sacrificing the size of memory pools and number of page table entries. If using Unified Memory Architecture (UMA)-based video hardware or an Accelerated Graphics Port (AGP), then it will require page table entries to address the video memory. ATI recommends one doesn't enable large system cache to avoid data corruption. More Info MS KB Q895932
More Info MS Technet - File Cache Performance and Tuning (Good read)
More Info MS Technet - Optimizing your memory configuration
More Info MS KB Q232271
More Info MS KB Q228766
More Info MS KB Q837331
Updated: 19 March 2009