By default, Windows Server 2003 caches all disk read and disk write operations. Cache Manager works closely with the memory manager and the file system to cache file system data in memory. This cache is flushed periodically and replaced with fresh data.
- Logical block caching
This caches disk sector data in memory.
- Virtual block caching
This caches data at the file system level instead of at the disk level.
Virtual cache sizeIA-32 architecture limits the size of virtual address space to 32 bits. If your computer is configured with the /3 GB switch, 3 gigabytes (GB) of virtual address space is reserved for user mode operation, and only 1 GB is available for kernel mode operation. The virtual cache size depends on the following factors:
- The physical memory in your computer.
- The value of the LargeSystemCache entry in the following registry subkey:KEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\MemoryManagementSet this value to 1 to enable this entry.
- The setting of the PagedPoolSize registry subkey during initialization.
- The use of the /3 GB switch.
- The boot image size.
- The session space size that is required for Terminal Server configuration.
|Architecture||Virtual cache size|
|IA-32||128 megabytes (MB) + (Physical memory - 16 MB) / 4 MB x 64 MB|
|IA-64||128 MB + (Physical memory - 16 MB) / 8 MB x 64 MB|
The following table indicates the maximum and the minimum limits for the virtual cache size calculation:
|Architecture||Minimum virtual cache size||Maximum virtual cache size|
|IA-32 (LargeCacheSize value = 0)||Not available||512 MB|
|IA-32 (LargeCacheSize value = 1)||Not available||960 MB|
|IA-64||128 MB||1 terabyte|
Note The /3GB switch reduces the size of virtual cache space by approximately 10 MB.
Physical cache sizeThere is no limit to the physical cache size in the IA-32 and IA-64 architectures. Windows allocates physical cache memory based on the following factors:
- Virtual cache data
- Cached file input/output
- The other demands that the system makes on physical memory
Cache flush frequencyIf the Cache Manager does not try to write modified file data back to a file, and free memory becomes scarce, the memory manager's modified writer thread writes the unwritten data back to a file. The system does not rely on the memory manager to flush file data back to the disk. Instead, the Cache Manager tries to write the data back to nonvolatile storage in a timely manner by using the "lazy writing" process. As programs modify file data, the Cache Manager keeps track of how much data is modified, or "dirty." The Cache Manager writes back one-eighth of the cache's modified data to disk every second.
ID articolo: 837331 - Ultima revisione: 30 apr 2008 - Revisione: 1