Disk Space Needed to Save UNFORMAT Information

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The following error message is displayed when the FORMAT commandcannot find enough free space on the disk to save the UNFORMATinformation:
Drive <x> error. Insufficient space for the MIRROR image file.
There was an error creating the format recovery file.
This disk cannot be unformatted.
Proceed (y/n)
Note: <x> refers to either drive A or B or any other external drive.

When the FORMAT command is used without the "/U" option, it tries tosave the UNFORMAT information when reformatting a disk to the samedensity. The following is the minimum space required in the last 25percent of the disk space for the FORMAT command to create a MIRRORimage file:
   Disk Size       Capacity      Free Space Needed   ---------       --------      -----------------   5.25 inches     360K           7,168 bytes   5.25 inches     1.2 MB        12,800 bytes   3.5 inches      720K           8,192 bytes   3.5 inches      1.44 MB       13,824 bytes				
The FORMAT command in MS-DOS version 5.0 examines the disk todetermine if it has already been formatted. If the disk has beenformatted, the FORMAT command attempts to create a MIRROR image filebefore reformatting the disk. When FORMAT finds that there is notenough room on the disk to create a MIRROR image file, it displays theerror message and gives you an option to continue with FORMAT. If youchoose to continue, the MIRROR image file is not created, and theUNFORMAT command will not be able to recover the old information fromthe newly formatted disk.

A MIRROR image file contains the information that the UNFORMAT commandneeds to unformat the disk. MIRROR image files can also be createdwith the MIRROR command. For more information on MIRROR, FORMAT, andUNFORMAT, query on the following words:
mirror and unformat
The UNFORMAT information consists of Boot Sector, File AllocationTable, and Root Directory, which is stored in the MIRROR image file.

The requirement of free space in the last 25 percent of the disk spaceis imposed to prevent UNFORMAT from taking an extensive amount of timewhen trying to find the control file anywhere on the disk.
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Article ID: 71585 - Last Review: 02/27/2014 21:01:44 - Revision: 1.0

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