Microsoft KB Archive/97741

= Optimizing DoubleSpace on Your Computer =

Article ID: 97741

Article Last Modified on 8/9/2007

-

APPLIES TO


 * Microsoft MS-DOS 6.0 Standard Edition
 * Microsoft MS-DOS 6.2 Standard Edition
 * Microsoft MS-DOS 6.22 Standard Edition
 * Microsoft Windows 95
 * Microsoft Plus! 95 Standard Edition

-



This article was previously published under Q97741



SYMPTOMS
NOTE: This information applies to both Microsoft DoubleSpace and Microsoft DriveSpace. For MS-DOS 6.22, Windows 95, and Microsoft Plus!, use DRVSPACE in place of DBLSPACE in all commands and file names.

After you use DoubleSpace to compress your hard disk, you may experience one or more of the following symptoms:


 * You may have less free conventional memory. As a result, you may be unable to run one or more MS-DOS-based programs. If you are running Windows 95 or Microsoft Plus! DriveSpace, the problem may occur only when you restart your computer in MS-DOS mode or boot to a Windows 95 command prompt.
 * You may experience a slight performance degradation.



CAUSE
To provide access to compressed drives, DoubleSpace loads a real-mode device driver that requires a considerable amount of memory. If your computer is not configured to provide access to the upper memory area (UMA), the DoubleSpace driver must load in conventional memory.

Windows 95 and Microsoft Plus! include both real-mode and protected-mode DriveSpace drivers. The real-mode DriveSpace driver is used to provide access to compressed drives before Windows 95 starts and when you restart your computer in MS-DOS mode or boot to a Windows 95 command prompt. The protected-mode DriveSpace driver is used after Windows 95 starts to provide protected-mode access to compressed drives.

Because the protected-mode DriveSpace driver replaces the real-mode driver in memory after Windows 95 starts, the amount of conventional memory used by the real-mode driver is normally not a concern when you are running MS- DOS-based programs in Windows 95. However, if you frequently run MS-DOS- based programs after restarting the computer in MS-DOS mode or after booting to a Windows 95 command prompt, you may find that programs requiring large amounts of conventional memory are unable to run.

The primary reason for performance degradation while running compression software such as DoubleSpace is that each time a read or write is made from or to the hard disk, data must be decompressed or compressed. This decompression or compression of data places additional demand on the processor in your computer. Computers with faster processors most likely will not experience performance degradation after compression software is installed.



RESOLUTION
To resolve the problem, refer to the appropriate section below.

MS-DOS 6.0, 6.2, or 6.22
To work around this problem when you are running MS-DOS 6.0, 6.2, or 6.22 DoubleSpace or DriveSpace, follow these steps:

 If you are using Microsoft Windows, set the TEMP environment variable to the host drive. To do so, follow these steps:

 Type dblspace /list at a command prompt and then press ENTER to determine which drive is the host drive. Use the DIR command to determine if you have at least two megabytes (MB) of free disk space on the host drive. If you do not, see the section titled &quot;Using DoubleSpace to Manage Compressed Drives&quot; in the &quot;User's Guide&quot; for instructions on decreasing the size of the compressed volume file (CVF). If you receive the message &quot;Drive X is too fragmented to resize,&quot; see section 7.14 in the Readme.txt file. Change to the host drive and create a TEMP directory. For example, if your host drive is drive H, type the following lines at a command prompt, pressing ENTER after each line:

h:

md \temp

  Using a text editor such as MS-DOS Editor, edit the Autoexec.bat file and change the SET TEMP statement to point to the TEMP directory on the host drive. For example:         set temp=h:\temp </ol> </li> If your computer contains an 80386 or higher processor, run MemMaker after you run DoubleSpace to ensure you are freeing as much convention- al memory as possible. If you have a VGA display adapter, run MemMaker in custom mode and choose Yes when you are prompted to use the mono- chrome region to obtain an additional 32K of upper memory block (UMB) space. If you have a Super VGA video display adapter, you can use the monochrome region, but you need to load the Monoumb.386 file if you use Microsoft Windows. For specific instructions, see section 2.3 of the Readme.txt file.</li> If your computer contains an 80286 processor and is low on conventional memory, consider purchasing a third-party memory manager to load device drivers, terminate-and-stay-resident (TSR) programs, and the Double- Space component (Dblspace.bin) in the upper memory area (UMA).</li> If your computer contains an 80286 or higher processor and has more than 1 MB of memory, ensure you are loading SMARTDrive.</li> If you are unable to run a particular program (such as an MS-DOS-based game) due to insufficient memory, you may want to move that software to the host drive and create a startup disk for drive A that does not contain the DoubleSpace component. To do so, follow these steps:

<ol style="list-style-type: lower-alpha;"> Type dblspace /list at a command prompt and then press ENTER to determine which drives are uncompressed or host drives.</li> Use the XCOPY command to copy the program's directory to the host drive. For example, if drive H is your host drive, type xcopy c:\dir\*.* h:\dir\*.* /s at a command prompt and then press ENTER.</li> Create a bootable floppy disk in drive A with the SYS command. For example, type sys c: a: at a command prompt and then press ENTER.</li> Type deltree a:\dblspace.bin at a command prompt and then press ENTER to remove the DoubleSpace component.</li> Confirm that all the files were copied to the host drive.</li> Using a text editor such as MS-DOS Editor, create Config.sys and Autoexec.bat files on drive A and include any TSRs or device drivers required by the program. You should also add a PATH statement to include the program's directory.

NOTE: If you are using a host drive, remember that the drive letter is different when you start the computer without the DoubleSpace component.</li> Restart the computer with the new startup disk in drive A and run the program to ensure you have configured the system correctly.

NOTE: Your compressed drive will not be accessible when you restart your computer from this floppy disk. However, the data on your drive is not lost. It will be accessible when you restart your computer from the hard disk.</li> If everything is functioning correctly, restart your computer from the hard disk and delete the program's directory from the compressed drive. For example, type deltree /y c:\dir at a command prompt and then press ENTER.</li></ol> </li> Some programs either implicitly (such as Microsoft Mail version 3.0) or explicitly (such as Paradox) encrypt data files. This encryption removes any patterns in the data, rendering it incompressible. Storing these files on a DoubleSpace drive does not save any disk space and increases file write time because DoubleSpace does the work of trying to compress the file, but cannot. These types of files, if updated often, should be stored on a uncompressed or host drive.</li></ol>

Windows 95 or Microsoft Plus!
Optimizing Performance with Windows 95 or Microsoft Plus! DriveSpace:

To optimize your computer's performance while running Windows 95 or Microsoft Plus! DriveSpace, follow these steps:

<ol> Verify that the protected-mode DriveSpace driver is being used in Windows 95. To do so, double-click the System icon in Control Panel, and then click the Performance tab. If the Disk Compression line indicates that compressed drives are using MS-DOS Compatibility mode, the protected-mode DriveSpace driver is not being used.

To cause the protected-mode DriveSpace driver to load when Windows 95 starts, follow these steps:

<ol style="list-style-type: lower-alpha;"> Make sure that the Drvspacx.vxd file is present in the Windows\ System\Iosubsys folder. If the file is not present, extract it to that folder from the Win95_09.cab cabinet file on the original Windows 95 CD-ROM or disk 9, or from the Plus_1.cab cabinet file on the original Microsoft Plus! CD-ROM or disk 1.

For information about using the Extract tool, type extract at a command prompt, or see the following article in the Microsoft Knowledge Base:

129605 How to Extract Original Compressed Windows Files

</li> Copy the Drvspace.bin file from the Windows\Command folder to the root folder of the boot drive as both Drvspace.bin and Dblspace.bin. To do so, type the following lines at a command prompt, pressing ENTER after each command

copy c:\windows\command\drvspace.bin :\drvspace.bin /y

copy c:\windows\command\dblspace.bin :\dblspace.bin /y

where is the physical boot drive. If drive C is compressed, copy the Drvspace.bin file to the root folder of the host drive for drive C instead of the root folder of drive C.

NOTE: The /Y switch causes the COPY command to replace existing files without prompting you for confirmation. After performing these steps, restart your computer and check to see if the problem has been resolved. If it has not, perform the following additional step:

</li> <li>If you did not extract the Drvspacx.vxd file in step A because it already exists in the Windows\System\Iosubsys folder, extract it now. In addition, extract the Drvspace.bin file from disk 1 or the CD-ROM to the Windows\Command folder. After extracting this file, repeat step B.</li></ol> </li> <li>Verify that the hard disks are not badly fragmented. Badly fragmented hard disks can affect the performance of DriveSpace 3, as well as the performance of other Windows 95 components. To ensure that your hard disks are not badly fragmented, run Disk Defragmenter to defragment them. To run Disk Defragmenter, click the Start button, point to Programs, point to Accessories, point to System Tools, and then click Disk Defragmenter.</li> <li>Verify that the drive containing your Windows folder and the Windows swap file contains sufficient free disk space. For information about creating additional free disk space, view the &quot;Disk Space Trouble- shooter&quot; topic in Windows 95 Help.</li></ol>

Optimizing Conventional Memory for MS-DOS-Based Programs:

If you are unable to run an MS-DOS-based program when you restart your computer in MS-DOS mode or boot to a Windows 95 command prompt after running Windows 95 or Microsoft Plus! DriveSpace, reconfigure Windows 95 so that more conventional memory is available. To do so, use one of the following methods:

<ul> <li>If you are running an MS-DOS-based program after restarting your computer in MS-DOS mode, modify the Config.sys and Autoexec.bat files that are used when the computer restarts in MS-DOS mode so that more conventional memory is available. You should modify the Config.sys and Autoexec.bat files that are specified in the properties for the program you are running in MS-DOS mode, the properties for the shortcut that starts the program you are running in MS-DOS mode, or the properties for the &quot;Exit to Dos.pif&quot; file that is used to start Windows 95 in MS-DOS mode.

Use the following steps to modify the Config.sys and Autoexec.bat files that are used when the computer restarts in MS-DOS mode so that more conventional memory is available. After performing each step, check to see if you are able to run the MS-DOS-based program.

<ol style="list-style-type: lower-alpha;"> <li> Make sure that the Config.sys file that is used when the computer restarts contains lines similar to the following (in the following order): <pre class="fixed_text">        DEVICE=C:\WINDOWS\HIMEM.SYS DEVICE=C:\WINDOWS\EMM386.EXE NOEMS DOS=HIGH,UMB DEVICEHIGH=C:\WINDOWS\COMMAND\DRVSPACE.SYS /MOVE These lines make it possible for the real-mode DriveSpace driver to load into upper memory, which can free more conventional memory for MS-DOS-based programs.

NOTE: If your MS-DOS-based program requires expanded memory, please see the program's documentation for information about how to configure Emm386.exe to provide expanded memory. </li> <li>Try loading device drivers in the Config.sys file using the DEVICEHIGH command instead of the DEVICE command. In addition, try loading memory-resident programs in the Autoexec.bat file using the LOADHIGH command.</li> <li>Remove any unnecessary drivers and memory-resident programs from the Config.sys and Autoexec.bat files that are used when you restart your computer in MS-DOS mode.</li></ol> </li> <li>Use the Microsoft Startup Disk Wizard (Nocomp.exe) that is included with Microsoft Plus! to create a bootable floppy disk that does not load the real-mode DriveSpace driver. To run an MS-DOS-based program after booting from the floppy disk created by the Microsoft Startup Disk Wizard, the program must be installed on an uncompressed drive.</li></ul>

<div class="moreinformation_section">

MORE INFORMATION
The DriveSpace compression drivers included with Windows 95 contain processor-specific code designed for optimal performance on 80386 and 80486 processors. In addition, the DriveSpace 3 compression drivers included with Microsoft Plus! contain code designed for optimal performance on Pentium processors. The compression drivers included with Windows 95 and Microsoft Plus! detect the type of processor that a computer is using and then use the appropriate code.

Microsoft Plus! includes DriveSpace 3, which is an enhanced version of DriveSpace that supports the ability to fine-tune compression for maximum disk space, maximum system speed, or a balance between disk space and system speed. If system performance is your primary concern, DriveSpace 3 can be configured accordingly, but doing so will cause your files to take up considerably more disk space.

Additional query words: 6.00 6.20 6.22 slow Ultima 6 Commander Keen Serpent Great Battles of the NorthWest

Keywords: kbfaq KB97741

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© Microsoft Corporation. All rights reserved.