mirror(CMD) 19 June 1992 mirror(CMD) Name mirror - record information about one or more disks Syntax mirror [drive:[ ...]] [/1] [/tdrive[-entries][ ...]] mirror [/u] mirror [/partn] To save information about the disk in the current drive, use the follow- ing syntax: mirror Parameter drive: Specifies the drive containing the disk for which you want mirror to save information. This information is used by the unformat command to restore a disk. Switches /1 Retains only the latest information about the disk. If you do not specify this switch, mirror makes a backup copy of the exist- ing disk-information file before recording the current informa- tion. /tdrive[-entries] Loads a terminate-and-stay-resident deletion-tracking program that records information used by the undelete command to recover deleted files. The required drive parameter specifies the drive containing the disk for which you want mirror to save information about deleted files. The optional entries parameter, which must be a value in the range 1 through 999, specifies the maximum num- ber of entries in the deletion-tracking file (PCTRACKR.DEL). The default value for entries is dependent upon the type of disk being tracked. The following list shows each disk size, its default number of entries, and its corresponding file size: _____________________________________________________________ Disk size Entries File size _____________________________________________________________ 360K 25 5K 720K 50 9K 1.2 megabyte (MB) 75 14K 1.44 MB 75 14K 20 MB 101 18K 32 MB 202 36K >32 MB 303 55K _________________________________________________________________________ CAUTION Do not use deletion tracking for any drive that has been redirected by using the join or subst command. If you intend to use the assign command, you must do so before using mirror to install deletion tracking. _________________________________________________________________________ /u Unloads the deletion-tracking program from memory, disabling deletion tracking. You cannot unload the tracking program if you loaded any other memory-resident programs after it. /partn Saves system information about how a hard disk is partitioned. The switch saves the information in a file on a floppy disk. The unformat command can use this file later to rebuild the parti- tions of a disk. Notes Saving information about a disk The mirror program saves a copy of the file allocation table and the root directory of the disk in the specified drive. The unformat command can use this information to rebuild a disk that has been unintentionally for- matted, or it can use the information to recover files and subdirectories in the disk's root directory. Because unformat restores the disk's system area to the condition it was in when you last used mirror, you should save this information frequently for every hard disk drive in your system. To ensure that the information is saved each time you turn on your computer, you may want to add a mir- ror command to your AUTOEXEC.BAT file. Removing the deletion-tracking program from memory You may need to remove the deletion-tracking program from memory. To do so, remove all memory-resident programs that you loaded after the deletion-tracking program, and then use the mirror command with the /u switch. Since this turns off deletion tracking, any files deleted after you remove the tracking program can be recovered only by using informa- tion in the directory. Saving information about hard-disk partitions Every formatted hard disk drive has at least one partition. To identify a hard disk drive, MS-DOS uses information stored in a special disk par- tition table. If this table is corrupted, MS-DOS cannot locate the hard disk. You can save partition-table information for a hard disk by using the mirror command with the /partn switch. This switch creates a file named PARTNSAV.FIL, which the unformat command can use to rebuild the partition table. Because MS-DOS cannot gain access to your hard disk if the parti- tion table is damaged, you should not put this file on the hard disk itself. Instead, you should put the file on a floppy disk (which you should keep in a safe place) or on another hard disk drive, such as a network server. Examples To save a copy of the file allocation table and the root directory of drive C and to install deletion tracking for drives A and C, type the following command: mirror c: /ta /tc Suppose you want to save a copy of the file allocation table and the root directory of the disk in the current drive, and you want to install the deletion-tracking program for drive C. To do this and to set the maximum number of deletions to be tracked to 500, type the following command. (Note that since no drive parameter is specified, mirror saves the infor- mation about the disk in the current drive.) mirror /tc-500 To save a copy of the partition table for your hard disk drive, type the following command: mirror /partn The mirror program displays the following information: Disk Partition Table saver. The partition information from your hard drive(s) has been read. Next, the file PARTNSAV.FIL will be written to a floppy disk. Please insert a formatted diskette and enter the name of the diskette drive. What drive? A The default disk drive is drive A. If you want to use a different drive, type the drive letter (making sure it does not identify a partition on the hard disk drive), insert a formatted floppy disk in the drive (if necessary), and press Enter. Related commands For information about retrieving deleted files, see the undelete(CMD) command. For information about restoring formatted disks, see the unformat(CMD) command.