readme.txt

优化系统速度

                                
                                
                   ===========================
                          vRamDir 1.10
                   for Microsoft Windows 95/98
                   ===========================
                                
                                
                       Copyright 1996-1998
                  Virtual Software Corporation
                         15016 SE 63 St.
                     Bellevue, WA 98006-4634
                    http://www.virtusoft.com/
                      [e-mail]
                       Fax: [phone]


vRamDir is a dynamic 32-bit virtual RAM file system driver for
Windows 95/98.


A. Introduction
B. Advantages of vRamDir over Hard-disks
C. Advantages of vRamDir over RAM-disks
D. Advantages of vRamDir over Disk-Cache
E. Installation
F. Usage
G. Benchmarks
H. Where to Get the FREE Trial Version of vRamDir
I. Limit of the Trial Version
J. How to Order vRamDir
K. Technical Support
L. License and Disclaimer


   ============
A. Introduction
   ============

   vRamDir is a dynamic 32-bit virtual RAM file system driver for
   Windows 95/98. It is to replace RAM-disk and speed up hard-disk
   related operations. vRamDir is over 30 times faster than hard-
   disks, 5 times faster than RAM-disks, and 2 times faster than
   disk-cache. vRamDir also keeps hard-disks less fragmented,
   saves hard-disk wears and tears, and saves battery power on
   notebook computers.
   
   vRamDir does not pre-allocate any memory, and it has no
   practical limit on the amount of files it can hold. No matter
   how much RAM your system has, vRamDir puts it into more
   efficient use and speeds up the system. If the system has more
   than 32MB RAM, vRamDir prevents the RAM from being wasted; if
   the system has less than 16MB RAM, it is important to use
   vRamDir to increase system speed.


   =====================================
B. Advantages of vRamDir over Hard-disks
   =====================================

   vRamDir is tens and thousands of times faster than hard-disks.

   vRamDir creates file systems in Random Access Memory (RAM) to
   simulate hard-disks.
   
   In access time, RAM is thousands of times faster than hard-
   disks. Locating an address in RAM takes 50-100ns, while
   seeking to a sector on a hard-disk takes 5-20ms. So RAM access
   is about 100,000 times faster.
   
   In throughput, RAM is tens of times faster than hard-disk.
   Reading/writing one block of data in RAM is about 20-100MB/s,
   while on hard-disks it is 1-2MB/s. So RAM throughput is 10-100
   times faster.
   
   By using vRamDir file systems, file operations are tens and
   thousands of times faster than hard-disks.
   
   vRamDir keeps the hard-disks less fragmented. Without vRamDir,
   temporary files scatter around on hard-disks. This can be
   prevented by creating the temporary files in vRamDir. Less
   fragmented hard-disks result in faster hard-disk access.
   
   vRamDir saves wears and tears of hard-disks. Hard-disks have
   mechanical parts and thus have much shorter life-spans than
   RAM. When accessing files in vRamDir, hard-disks are not
   accessed. Thus hard-disks are less probable to fail, and hard-
   disks live longer, hence it is less likely to lose your data
   on hard-disks.
   
   vRamDir saves battery power on notebook computers. When hard-
   disks are less often accessed because of vRamDir, less power
   is consumed by hard-disks, and the battery runs longer.


   =============================================
C. Advantages of vRamDir over RAM-Disk Utilities
   =============================================

   vRamDir is several times faster than RAM-disk utilities.

   vRamDir is a 32-bit protected-mode Windows 95/98 native virtual
   device driver (VxD), while RAM-disk utilities are 16-bit real-
   mode DOS device drivers. With RAM-disks, Windows 95/98 needs to
   switch forth and back between 16-bit real-mode and 32-bit
   protected-mode. This very time consuming mode switching is
   avoided in vRamDir. For example, when benchmarked against
   RAMDRIVE, vRamDir is more than 4 times faster.
   
   vRamDir is dynamic. When there is no file in vRamDir, vRamDir
   does not allocate any memory. RAM-disks, on the other hand,
   pre-allocate fixed amount of memory. Even when the memory is
   not used by files on a RAM-disk, the memory is no longer
   available to system and application programs. With vRamDir, no
   extra memory is taken, more memory is available to the system,
   and the system runs faster.
   
   When more files need to be on RAM-disk than the fixed amount
   pre-allocated, RAM-disk is not able to hold them. The
   operation will fail, and your application or even the system
   may crash as a result. With vRamDir, it expands on demand.
   There is no practical limit on the number of files and the
   size of files that can fit into vRamDir. (The limit is the
   total amount of physical memory plus the free hard-disk space
   in your system, which is even larger than what is available
   without vRamDir, the free hard-disk space alone.)
   
   vRamDir is virtual. vRamDir can return memory back to the
   system, while RAM-disks can never do that. When other
   applications need more memory, files in vRamDir can be saved
   onto hard-disks and memory is returned to system. You never
   need to worry about vRamDir using too much memory. vRamDir
   makes sure that it always puts memory into the best use and
   that the system runs as fast as possible.
   
   vRamDir creates virtual file systems, while RAM-disks create
   disk images on which to build FAT file systems. Disks are
   block devices and have limitations. For example, on a disk
   even when only 1-byte is used in a block, the rest is not
   available to other files. RAM is different from disks. It is
   not efficient to use RAM in the same block manner as disks.
   FAT file system has further limitations. In RAM-disks, e.g.,
   space needs to be pre-allocated for File Allocation Tables
   (FAT), the block size and the number of entries in the root
   directory, etc., needs to be pre-determined. vRamDir avoids
   the limitations of block devices and the FAT system. vRamDir抯
   file system is virtual and much more efficient. There is no
   setting needs to be fine-tuned.
   
   vRamDir maps directories into RAM, while RAM-disks create new
   drives. With vRamDir, it is easy to map existing directories,
   e.g., TEMP directories, into RAM. There is no new drive letter
   to worry about. Existing settings for the system and
   applications do not need to be changed to point to the new
   drive letter. vRamDir is very easy to set up, and the system
   runs exactly like before, except that with vRamDir it will be
   much faster.
   
   vRamDir supports Long File Name, while RAM-disks only support
   short name.
   
   
   ===============================================
D. Advantages of vRamDir over Disk-Cache Utilities
   ===============================================

   vRamDir is several times faster than disk-cache utilities.
   
   vRamDir is not designed to replace disk-cache, but vRamDir
   does something that disk-cache can not do. Disk cache cannot
   replace vRamDir. They are used for different purposes.
   
   Disk-cache keeps most recently accessed files in memory. You
   do not have control of what to keep in the cache and what not.
   vRamDir let you control what to be put in RAM. vRamDir is
   designed to speed up temporary file access.
   
   vRamDir is much faster than disk-cache in the best
   circumstances. Many applications create temporary files on
   hard-disks. With disk-cache, when a temporary file is created,
   it will stay in memory for a short while. Then within, e.g., 1
   second, disk cache will write the file out to hard-disks,
   which is very slow. With vRamDir, files can stay in memory
   much longer. A temporary file may stay in memory during its
   entire existence, from the point it is created, to the point
   it is deleted. Hard-disks may never need to be accessed in
   these temporary file operations.
   
   vRamDir is still several times faster than disk-cache overall,
   even in the worst situations. For example, WINBENCH抯 disk/mix
   test, which emulates popular applications