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SCANDISK--Notes

Problems fixed by ScanDisk ScanDisk checks and fixes problems in the following areas of each drive: * File allocation table (FAT) * File system structure (lost clusters, crosslinked files) * Directory tree structure * Physical surface of the drive (bad clusters) In addition, ScanDisk also checks and fixes the following areas of a DriveSpace or DoubleSpace compressed drive: * Volume header (MDBPB) * Volume file structure (MDFAT) * Ccompression structure * Volume signatures * MS-DOS boot sector Types of drives ScanDisk can find and fix errors on the following types of drives: * Hard drives * DriveSpace drives * DoubleSpace drives (if DoubleSpace is installed) * Floppy disk drives * RAM drives * Memory cards ScanDisk cannot find or fix errors on the following types of drives: * CD-ROM drives * Network drives * Drives created by using the ASSIGN, SUBST, or JOIN commands * Drives created by using INTERLNK Using ScanDisk when other programs are running Do not use ScanDisk to repair a drive when other programs are running. ScanDisk is designed for use when files on a disk are in an unchanging state. When you are using a file, MS-DOS updates the file allocation table (FAT) and the directory structure to reflect changes. Such updates are not always made immediately. If you run ScanDisk when other programs are running, files might still be open. ScanDisk interprets differences between the directory structure and the file allocation tables as errors. This can result in corruption or loss of data. You cannot use ScanDisk to correct disk errors if you start it from another program, or when Microsoft Windows or MS-DOS Task Swapper are running. However, you can check your disk without fixing errors by using the SCANDISK command with the /CHECKONLY switch. If you run it with Windows, ScanDisk might detect errors that do not exist when Windows is not running. Using ScanDisk with PC-DOS 6.1 Do not run ScanDisk on any PC-DOS 6.1 compressed drive. If you do, you will lose all data on that drive. ScanDisk is compatible only with MS-DOS compressed drives (DriveSpace drives and DoubleSpace drives) and is not designed to run on PC-DOS compressed drives. Using ScanDisk on DoubleSpace Drives If DoubleSpace is installed (that is, if DBLSPACE.BIN is loaded into memory), ScanDisk can check and repair DoubleSpace drives and unmounted DoubleSpace compressed volume files. ScanDisk can also check and repair DoubleSpace drives and volume files if the DBLSPACE.BIN and DRVSPACE.MR1 files are available. Otherwise, ScanDisk does not work on DoubleSpace drives or unmounted DoubleSpace compressed volume files. For more information about the DRVSPACE.MR1 file, see DBLSPACE--Notes. (For more information about using DoubleSpace with MS-DOS 6.22, see <DBLSPACE>.) The SCANDISK.INI file The SCANDISK.INI file is a text file located in the directory that contains your MS-DOS files. The settings in the [Environment] section of the SCANDISK.INI file determine certain aspects of ScanDisk's behavior, such as whether it is configured for a monochrome or color display. The settings in the [Custom] section determine the default behavior of ScanDisk when you start it with the /CUSTOM switch. For more information, read the comments in the SCANDISK.INI file. Undoing the changes ScanDisk made If ScanDisk finds errors on your drive, the program gives you the option of creating an Undo disk, which enables you to undo the changes ScanDisk makes to your drive. The Undo disk contains information that specifies which drive it applies to as well as information on every change that ScanDisk made to that drive. CAUTION: Use the Undo disk to undo changes only if your drive has not changed since that Undo disk was created. If you changed any of the files on your drive since you created the Undo disk, do not try to undo your changes. If you attempt to use the Undo disk after you update a file or directory, or copy or delete a file, you might damage your drive structure and lose data. ScanDisk Errorlevels When ScanDisk returns to the command prompt, it sets ERRORLEVEL to one of the following: 0 ScanDisk did not detect any problems on the drive(s) it checked. 1 ScanDisk could not run because the command-line syntax was incorrect. 2 ScanDisk terminated unexpectedly due to an out-of-memory error or an internal error. 3 The user chose to exit before ScanDisk had finished. 4 ScanDisk completed all logical checks on all drives, but the user exited from one or more surface scans before the scans were complete. Errorlevel 4 is not returned if the user chose to bypass the surface scans completely. 254 ScanDisk found disk problems and corrected them all. 255 ScanDisk found disk problems, but not all problems were corrected.
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