DOCUMENT:Q138629 08-AUG-2001 [winnt] TITLE :How Windows NT 3.51 Handles Compression of Paging Files PRODUCT :Microsoft Windows NT PROD/VER:3.51 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Workstation version 3.51 - Microsoft Windows NT Server version 3.51 ------------------------------------------------------------------------------- SUMMARY ======= Windows NT provides virtual memory by creating a paging file (PAGEFILE.SYS) in the root directory of the boot drive or the root directory of the Windows NT drive (the drive where Windows NT is installed). In Windows NT 3.51, the Windows NT file system (NTFS) file system supports on-the-fly compression and decompression of files and directories. This article explains how Windows NT 3.51 handles file compression of paging files. MORE INFORMATION ================ File compression in the NTFS partition is accomplished by reallocating the file during the operation. Since you cannot reallocate the paging file while it is being used, compression of an active paging file is not allowed. When you compress a file in the NTFS partition, the file is reallocated as new data is written to the file. Because reallocation of the paging file is not allowed while servicing a page fault, NTFS prevents compression on active paging files. No message appears notifying the user that this operation is not allowed. If you have multiple installed versions of Windows NT 3.51 and multiple paging files on the same computer (each installation with its own paging file), compression of the inactive paging file is allowed. However, if you shutdown and restart another installed version of Windows NT with a compressed paging file, PAGEFILE.SYS is automatically uncompressed. Additional query words: prodnt compact ====================================================================== Keywords : Technology : kbWinNTsearch kbWinNTWsearch kbWinNT351search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS351 kbWinNTS351search Version : 3.51 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.