NTFS includes several system files, all of which are hidden from view on the NTFS volume. A system file is one used by the file system to store its metadata and to implement the file system. System files are placed on the volume by the Format utility.
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| System File | File Name | MFT Record | MFT Record |
|---|---|---|---|
| Master file table | $Mft | 0 | Contains one base file record for each file and folder on an NTFS volume. If the allocation information for a file or folder is too large to fit within a single record, other file records are allocated as well. |
| Master file table | $Mft | 0 | Contains one base file record for each file and folder on an NTFS volume. If the allocation information for a file or folder is too large to fit within a single record, other file records are allocated as well. |
| Master file table 2 | $MftMirr | 1 | A duplicate image of the first four records of the MFT. This file guarantees access to the MFT in case of a single-sector failure. |
| Log file | $LogFile | 2 | Contains a list of transaction steps used for NTFS recoverability. Log file size depends on the volume size and can be as large as 4 MB. It is used by Windows NT/2000 to restore consistency to NTFS after a system failure. |
| Volume | $Volume | 3 | Contains information about the volume, such as the volume label and the volume version. |
| Attribute definitions | $AttrDef | 4 | A table of attribute names, numbers, and descriptions. |
| Root file name index | $ | 5 | The root folder. |
| Cluster bitmap | $Bitmap | 6 | A representation of the volume showing which clusters are in use. |
| Boot sector | $Boot | 7 | Includes the BPB used to mount the volume and additional bootstrap loader code used if the volume is bootable. |
| Bad cluster file | $BadClus | 8 | Contains bad clusters for the volume. |
| Security file | $Secure | 9 | Contains unique security descriptors for all files within a volume. |
| Upcase table | $Upcase | 10 | Converts lowercase characters to matching Unicode uppercase characters. |
| NTFS extension file | $Extend | 11 | Used for various optional extensions such as quotas, reparse point data, and object identifiers. |
| 12-15 | Reserved for future use. |
