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CHKDSK + Checking Disk Space

Reports disk size, space available, and RAM available. Also

reports and optionally corrects internal disk errors.


PC-DOS 2.0+ (revised from 1.0)

MS-DOS equivalent: CHKDSK (2.0+, revised from 1.0)




[d:][path] CHKDSK [cd:][cpath][cfilename][V]


[d:][path] Specifies the drive letter and

path name containing the

CHKDSK command file.

[cd:][cpath][cfilename] Specifies the file or files

(if wildcards are used) to be

checked. If omitted, all files

in the current directory are


/F Fixes errors in the File

Allocation Table (FAT).

/V Provides file names as it

examines them so that you can

see where errors occur.

CHKDSK is often used to verify the internal organization of

a disk or to check the amount of space available. It can also be

used to test for fragmented files. With the /F option, CHKDSK can

be used to repair common internal disk errors.



checks drive C, reporting any internal errors as well as disk

size, free space, and available RAM.


checks the disk in drive B while fixing any internal errors it

finds. You will be asked whether you wish to recover any lost

data sectors (allocation units) into data files. If you respond

Y, each lost allocation unit is recovered into its own file,

named FILEnnn.CHK. You can inspect the recovered units by using

the TYPE or DEBUG command. If they are needed, you can RENAME

them again or concatenate them using COPY; if not, you can delete



checks the file named REPORTS, reporting any noncontiguous areas

on the disk that are occupied by the REPORTS file. The more

noncontiguous areas CHKDSK reports, the greater the fragmentation

on the disk, which reduces disk operation speed. To eliminate

fragmentation, issue the BACKUP, FORMAT, and RESTORE commands to

back up the disk, reformat it, and then restore the backed-up

files to the disk, respectively.


checks the disk in drive B, repairing it while displaying a

series of messages indicating its progress and status.


All specified file(s) are contiguous

The files you specified are not fragmented (that is, they are not

stored in noncontiguous areas).

Cannot CHKDSK a network drive

You cannot use CHKDSK to check a network drive or a disk that is

being shared on a network. If the disk is shared, have the server

pause and then perform CHKDSK.

Cannot CHKDSK a SUBSTed or ASSIGNed drive

The SUBST command hides information that CHKDSK needs. Remove the

substitution and try again.

CHDIR..failed, trying alternate method

CHKDSK could not change directories. Restart DOS and issue CHKDSK


Convert lost chains to files (Y/N)?

Respond Y to convert lost data blocks to files. If you have used

the /F option, each chain will be recovered into a separate file.

If you enter N, CHKDSK frees the blocks so that they can be

allocated to new files.

Directory is joined,

tree past this point not processed.

The JOIN command has been used to join the drive to another

device. CHKDSK skips over joined devices.

Directory to file (Y/N)?

The directory that is being checked contains too much invalid

information to continue to be used as a directory. Enter Y to

convert the directory to a file that can be examined with DEBUG.

Enter N if you do not want the directory to be changed to a file.

Disk error reading/writing FAT x

The x portion of the FAT could not be updated. If this message

appears twice for FATs 1 and 2, format the disk. If FORMAT fails,

the disk is probably unusable.

[.].Entry has a bad attribute

(or size or link)

One period preceding this message indicates that the current

directory is in error; two periods indicates the parent

directory. Use the /F option to correct the error.

Error found, F parameter not specified

Corrections will not be written to disk

CHKDSK is analyzing but not correcting the disk. To correct the

disk, use the /F option.

File is cross-linked

on cluster xx

The same data block is linked to two different files.

filename Allocation error for file, size adjusted

The file allocation table contains an invalid file allocation

unit. The file is truncated after the last valid file allocation


filename Contains invalid cluster

[file truncated]

The file has an invalid pointer. If you have used the /F option,

the bracketed message is also reported.

filename Contains xxx non-contiguous blocks

The reported number of noncontiguous areas were found for that


filename File cluster number is invalid

[, entry truncated]

The file contains an invalid pointer. If you have used the /F

option, the file will be truncated and the bracketed message will


Insufficient room in root directory

Erase files from root and repeat CHKDSK

There is not enough room to convert lost blocks to files.

Invalid current directory

An unrecoverable read error was located on the disk; no action is


path Convert directory to file (Y/N)?

The directory has been determined to no longer be usable. Respond

Y to convert it to a file.

path Invalid subdirectory

The subdirectory contains invalid information. CHKDSK attempts to

correct the error. Use the /V option for more information.

Probable non-DOS disk.

Continue (Y/N)?

Either the disk being checked is not formatted properly or it is

badly damaged. If you have not specified the /F option,

responding Y tells CHKDSK to indicate corrective actions but not

to perform them.

Processing cannot continue,

This message is followed by another message that indicates the

reason CHKDSK is unable to continue.

Tree past this point not


Track 0 on the disk is bad, so the path past the directory that

is currently being checked could not continue.

Unrecoverable error on directory

An error was encountered in the directory; no action is required.

xxxxxxxxx bytes disk space freed

The indicated number of bytes of disk space was not allocated and

therefore was freed.

xxx lost clusters found in yyy chains

The indicated number of lost data blocks were not associated with

any file.


Running CHKDSK with the /F option can result in losing some

information, so you should first run CHKDSK without the /F

option. If CHKDSK reports errors, use the COPY command to copy

the files off the disk as backup; then run CHKDSK /F. If you

specify a file name or use the wildcard pattern *.*, CHKDSK

reports the number of noncontiguous areas that the file(s) occupy

on the disk. Version 1.0 of the command did not report available

disk space, hidden files, user files, and bad sectors. It

automatically ran with the /F option, fixing the disk while

checking it.


[For related topics, press R]


ASSIGN Command

BACKUP Command

CHDIR Command

COPY Command

FORMAT Command

LABEL Command

SELECT Command

SUBST Command

SYS Command

TYPE Command

VER Command

VOL Command


file: /Techref/dos/command/chkdsk.htm, 8KB, , updated: 2004/6/12 17:03, local time: 2017/10/18 15:18,

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