The ‘Typical role of this computer' Reference Document

[soporific]

Hi there!

In preparation for my forthcoming utility - Advanced Typical Role - i put this document together that combines all the necessary information to understand the settings, with my proposed 'Typical Role' templates. The utility willl be freeware and completely 'open' in all senses of the word and concept, as all my stuff is. I am a commie after all!! So please influence the development by commenting on the document below and adding any suggested changes, additions & deletions. Your contributions will be appropriately noted. A copy of the document can be found in the attachment.

The 'Typical role of this computer' Reference Document.

For Windows 98/98se machines.

The 'Typical role of this computer' setting can be found in:

Start - Settings - Control Panel - System - Performance - Advanced settings - File System.. - Hard Disk

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Registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\FileSystem

Values:

NameCache stores the locations of the most recently accessed file names. The combined use of PathCache and NameCache means that VFAT never searches the disk for the location of cached file names. Both PathCache and NameCache use memory out of the general system heap.

PathCache specifies the size of the cache that the virtual file allocation table (VFAT) can use to save the locations of the most recently accessed directory paths. This cache improves performance by reducing the number of times the file system must seek paths by searching the file allocation table.

ReadAheadThreshold sets the read-ahead buffer size for all drives installed in your system. Windows uses this memory dynamically to read ahead, only when opening files/folders, returning it back to the system afterwards. Read-ahead caching is a background function designed to improve a system's performance. It uses software to buffer requested data in cache memory, which resides directly on the CPU or motherboard. Read-ahead caching relies on the probability that when the user requests specific information, he will request closely related or sequential data next. Thus, the system reads ahead for this data and stores it in its buffered cache, where users can access it much quicker.

DriveWriteBehind specifies the size of the write behind cache. Most Windows systems, by default, have write-behind caching enabled. This speeds up disk-write operations by holding data in memory until the computer thinks it is the right time to write it to disk. This same feature can also cause conflicts with shared files and networked software .... Because the data is not being written directly to the hard drive on the spot, delays imposed by caching can cause a server or workstation to become confused and to cause data corruption. If this happens, the computer's 'disk write caching' functions should be disabled.

ContigFileAllocSize can be used to change the size of the contiguous space that VFAT searches for when allocating disk space. Under MS-DOS, the file system began allocating the first available space found on the disk, which ensured a great deal of disk fragmentation and related performance problems. By default under Windows 98, VFAT first tries to allocate space in the first contiguous 0.5 MB of free space and then returns to the MS-DOS method if it cannot find at least this much contiguous free space. This optimizes performance for both the swap file and multimedia applications. In some cases, you might choose to set a smaller value in the registry, as when you are not running demanding applications on the computer. A smaller value for ContigFileAllocSize, however, can lead to more fragmentation on the disk and, consequently, more disk access for the swap file or applications that require larger amounts of disk space.

BufferIdleTimeout, BufferAgeTimeout, and VolumeIdleTimeout control the time between when changes are placed in the buffer to when they are written to the hard disk.

DisableLowDiskSpaceBroadcast denies the Low Space dialog from popping up for drives A,C and D.

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Settings Legend:

NC=NameCache (no. of filenames)

PC= PathCache (no. of filepaths)

RAT = ReadAheadThreshold (in ?)

DWB=DriveWriteBehind (in ?)

CFAS=ContigFileAllocSize (in bytes)

Specs Legend:

MRRS= Minimum Recommended RAM Size (in MBs)

Some calculations:

251658240 = 1920kb

4294967295 = 24mb

Example reg file:

REGEDIT4

[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\FileSystem]

"DriveWriteBehind"=hex:ff,ff,ff,ff

"NameCache"=hex:ff,ff,00,00

"PathCache"=hex:ff,00,00,00

"ReadAheadThreshold"=hex:00,00,01,00

"DisableLowDiskSpaceBroadcast"=dword:0000001d

"ContigFileAllocSize"=dword:00000800

Sources:

http://www.mdgx.com/newtip18.htm#CDMC

http://www.microsoft.com/technet/archive/w...6.mspx?mfr=true

http://www.putergeek.com/win98_file_system/

An Introduction to Caching

TypcRole.zip