Partition Boot Sector is damaged

The Partition Boot Sector contains information, which the file system uses to access the volume. On personal computers, the Master Boot Record uses the Partition Boot Sector on the system partition to load the operating system kernel files. Partition Boot Sector is the first sector of the Partition.

For our first NTFS partition we have boot sector:

Physical Sector: Cyl 0, Side 1, Sector 1
000000000   EB 5B 90 4E 54 46 53 20  20 20 20 00 02 01 00 00   e[?NTFS    .....
000000010   00 00 00 00 00 F8 00 00  3F 00 FF 00 3F 00 00 00   .....o..?.y.?...
000000020   00 00 00 00 80 00 80 00  3F 32 4E 00 00 00 00 00   ....Ђ.Ђ.?2N.....
000000030   5B 43 01 00 00 00 00 00  1F 19 27 00 00 00 00 00   [C........'.....
000000040   02 00 00 00 08 00 00 00  10 EC 46 C4 00 47 C4 0C   .........iFA.GA.
000000050   00 00 00 00 00 00 00 00  00 00 00 00 00 FA 33 C0   .............u3A
000000060   8E D0 BC 00 7C FB B8 C0  07 8E D8 C7 06 54 00 00   Z??.|u?A.ZOC.T..
000000070   00 C7 06 56 00 00 00 C7  06 5B 00 10 00 B8 00 0D   .C.V...C.[...?..
000000080   8E C0 2B DB E8 07 00 68  00 0D 68 66 02 CB 50 53   ZA+Ue..h..hf.EPS
000000090   51 52 06 66 A1 54 00 66  03 06 1C 00 66 33 D2 66   QR.f?T.f....f3Of
0000000A0   0F B7 0E 18 00 66 F7 F1  FE C2 88 16 5A 00 66 8B   .·...f?n?A?.Z.f‹
0000000B0   D0 66 C1 EA 10 F7 36 1A  00 88 16 25 00 A3 58 00   ?fAe.?6..?.%.?X.
0000000C0   A1 18 00 2A 06 5A 00 40  3B 06 5B 00 76 03 A1 5B   ?..*.Z.@;.[.v.?[
0000000D0   00 50 B4 02 8B 16 58 00  B1 06 D2 E6 0A 36 5A 00   .P?.‹.X.±.O?.6Z.
0000000E0   8B CA 86 E9 8A 36 25 00  B2 80 CD 13 58 72 2A 01   ‹E†eS6%.?ЂI.Xr*.
0000000F0   06 54 00 83 16 56 00 00  29 06 5B 00 76 0B C1 E0   .T.?.V..).[.v.Aa
000000100   05 8C C2 03 D0 8E C2 EB  8A 07 5A 59 5B 58 C3 BE   .?A.?ZAeS.ZY[XA?
000000110   59 01 EB 08 BE E3 01 EB  03 BE 39 01 E8 09 00 BE   Y.e.?a.e.?9.e..?
000000120   AD 01 E8 03 00 FB EB FE  AC 3C 00 74 09 B4 0E BB   ­.e..ue?¬<.t.?.»
000000130   07 00 CD 10 EB F2 C3 1D  00 41 20 64 69 73 6B 20   ..I.eoA..A disk 
000000140   72 65 61 64 20 65 72 72  6F 72 20 6F 63 63 75 72   read error occur
000000150   72 65 64 2E 0D 0A 00 29  00 41 20 6B 65 72 6E 65   red....).A kerne
000000160   6C 20 66 69 6C 65 20 69  73 20 6D 69 73 73 69 6E   l file is missin
000000170   67 20 66 72 6F 6D 20 74  68 65 20 64 69 73 6B 2E   g from the disk.
000000180   0D 0A 00 25 00 41 20 6B  65 72 6E 65 6C 20 66 69   ...%.A kernel fi
000000190   6C 65 20 69 73 20 74 6F  6F 20 64 69 73 63 6F 6E   le is too discon
0000001A0   74 69 67 75 6F 75 73 2E  0D 0A 00 33 00 49 6E 73   tiguous....3.Ins
0000001B0   65 72 74 20 61 20 73 79  73 74 65 6D 20 64 69 73   ert a system dis
0000001C0   6B 65 74 74 65 20 61 6E  64 20 72 65 73 74 61 72   kette and restar
0000001D0   74 0D 0A 74 68 65 20 73  79 73 74 65 6D 2E 0D 0A   t..the system...
0000001E0   00 17 00 5C 4E 54 4C 44  52 20 69 73 20 63 6F 6D   ...\NTLDR is com
0000001F0   70 72 65 73 73 65 64 2E  0D 0A 00 00 00 00 55 AA   pressed.......U?

Offset       0  1  2  3  4  5  6  7   8  9  A  B  C  D  E  F

The printout is formatted in three sections:

• Bytes 0x00– 0x0A are the jump instruction and the OEM ID (shown in bold print).
• Bytes 0x0B–0x53 are the BIOS Parameter Block (BPB) and the extended BPB.
  This block contains such essential parameters as
  Bytes Per Sector (WORD, offset 0x0B),
  Sectors Per Cluster (BYTE, offset 0x0D),
  Media Descriptor (BYTE, offset 0x15),
  Sectors Per Track (WORD, offset 0x18),
  Number of Heads (WORD, offset 0x1A),
  Hidden Sectors (DWORD, offset 0x1C),
  Total Sectors (LONGLONG, offset 0x28), etc...
• The remaining code is the bootstrap code (that is necessary for the proper system boot) and the end of sector marker (shown in bold print).

This sector is so important on NTFS, for example, duplicate of the boot sector is located on the disk.
Boot Sector for FAT looks different, however its BPB contains parameters similar to the above mentioned. There is no extra copy of this sector stored anywhere, so recovery on FAT is as half as less successful than on NTFS.

What will happen if Partition Boot Sector is damaged or bad/unreadable?

Lets fill up with zeros several lines of Partition Boot Sector:

000000000   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000010   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000020   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000030   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000040   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000050   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000060   8E D0 BC 00 7C FB B8 C0  07 8E D8 C7 06 54 00 00   Z??.|u?A.ZOC.T..

If we try to boot, we'll see "Non System Disk” or “Disk Error..". After we fail to load from it and from floppy, partition becomes unbootable.

Because a normally functioning system relies on the boot sector to access a volume, it is highly recommended that you run disk-scanning tools such as Chkdsk regularly, as well as back up all of your data files to protect against data loss in case you lose access to the volume.

Tools like Active@ Partition Recovery and Active@ UNERASER allow you to create backup of MBR, Partition Table and Volume Boot Sectors so that if for some reason it fails to boot, you can always restore your partition information and have an access to files/folders on that partition.

What to do if this sector is damaged?

• If we do have backup of the whole disk or MBR/Boot Sectors we can try to restore it from there.
• If we do not have backup, in case of NTFS we could try to locate a duplicate of Partition Boot Sector and get information from there.
• If duplicate boot sector is not found, only virtual partition recovery might be possible if we can determine critical partition parameters such as Sectors per Cluster, etc..

How can we fix NTFS boot sector using standard Windows NT/2000/XP tools?

On NTFS copy of boot sector is stored at the middle or at the end of the Volume.
You can boot from startup floppy disks or CD-ROM, choose repair option during setup, and run Recovery 

Console. When you are logged on, you can run FIXBOOT command to try to fix boot sector.

How can recovery software help you in this situation?

• It can backup MBR, Partition Table and Boot Sectors and restore them in case of damage
• It can try to find out duplicate boot sector on the drive and re-create the original one or perform virtual data recovery based on found partition parameters
• Some advanced techniques allow assuming drive parameters even if duplicate boot sector is not found (i.e. perform virtual partition recovery) and give the user virtual access to the data on the drive to be able to copy them to the safer location.

 

Partition is deleted or Partition Table is damaged. Unformat.

                    The information about primary partitions and extended partition is contained in the Partition Table, a 64-byte data structure, located in the same sector as the Master Boot Record (cylinder 0, head 0, sector 1). The Partition Table conforms to a standard layout, which is independent of the operating system. The last two bytes in the sector are a signature word for the sector and are always 0x55AA.

For our disk layout we have Partition Table:

Physical Sector: Cyl 0, Side 0, Sector 1
0000001B0                                              80 01   ..............Ђ.   
0000001C0   01 00 07 FE 7F 3E 3F  00 00 00 40 32 4E 00 00 00   ...?>?...@2N...
0000001D0   41 3F 06 FE 7F 64 7F 32  4E 00 A6 50 09 00 00 00   A?.?d2N.¦P....
0000001E0   41 65 0F FE BF 4A 25 83  57 00 66 61 38 00 00 00   Ae.??J%?W.fa8...
0000001F0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 AA   ..............U?

We can see three existing and one empty entries:

• Partition 1, offset 0x01BE (446)
• Partition 2, offset 0x01CE (462)
• Partition 3, offset 0x01DE (478)
• Partition 4 - empty, offset 0x01EE (494)

Each Partition Table entry is 16 bytes long, making a maximum of four entries available. Each partition entry has fields for Boot Indicator (BYTE), Starting Head (BYTE), Starting Sector (6 bits), Starting Cylinder (10 bits), System ID (BYTE), Ending Head (BYTE), Ending Sector (6 bits), Ending Cylinder (10 bits), Relative Sector (DWORD), Total Sectors (DWORD).

Thus the MBR loader can assume the location and size of partitions. MBR loader looks for the "active" partition, i.e. partition that has Boot Indicator equals 0x80 (the first one in our case) and passes control to the partition boot sector for further loading.
Lets consider the situations which cause computer to hang up while booting or data loss.

1. What will happen if no partition has been set to the Active state (Boot Indicator=0x80)?
Lets remove Boot Indicator from the first partition:

0000001B0                                            00 01  ................   
0000001C0 01 00 07 FE 7F 3E 3F  00 00 00 40 32 4E 00 00 00  ...?>?...@2N...

When we try to boot now, we see an error message like "Operating System not found". It means that the loader cannot determine which partition is system and active to pass control to.

2. What will happen if partition has been set to the Active state (Boot Indicator=0x80) but there are no system files on that partition?

(it could happen if we had used for example FDISK and selected not the proper active partition).
Loader will try to boot from there, fails, try to boot again from other devices like floppy, and if fails to boot again, we'll see an error message like "Non-System Disk or Disk Error".

3. What will happen if partition entry has been deleted?

If it has been deleted, next two partitions will move one line up in the partition table.

Physical Sector: Cyl 0, Side 0, Sector 1
0000001B0                                              80 00   ..............Ђ.
0000001C0   41 3F 06 FE 7F 64 7F 32  4E 00 A6 50 09 00 00 00   A?.?d2N.¦P....
0000001D0   41 65 0F FE BF 4A 25 83  57 00 66 61 38 00 00 00   Ae.??J%?W.fa8...
0000001E0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
0000001F0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 AA   ..............U?

If we try to boot now, the previous second (FAT) partition becomes the first and the loader will try to boot from it. And if it's not a system partition, we'll get the same error messages.

4. What will happen if partition entry has been damaged?

Let's write zeros to the location of the first partition entry.

Physical Sector: Cyl 0, Side 0, Sector 1
0000001B0                                              80 00   ..............Ђ.
0000001C0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
0000001D0   41 3F 06 FE 7F 64 7F 32  4E 00 A6 50 09 00 00 00   A?.?d2N.¦P....
0000001E0   41 65 0F FE BF 4A 25 83  57 00 66 61 38 00 00 00   Ae.??J%?W.fa8...
0000001F0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 AA   ..............U?

If we try to boot now, the MBR loader will try to read and interpret zeros (or other garbage) as partition parameters and we'll get an error message like "Missing Operating System".

Thus, the second step in partition recovery is to run Disk Viewer and to make sure that the proper partition exists in the partition table and has been set as active.
 
How can recovery software help you in the above-mentioned scenarios?

1. Discover and suggest you to choose the partition to be active (even FDISK does so).
2. Discover and suggest you to choose the partition to be active.
3. Perform a free disk space scan to look for partition boot sector or remaining of the deleted partition information in order to try to reconstruct Partition Table entry for the deleted partition.
4. Perform all disk space scan to look for partition boot sector or remaining of the damaged partition information in order to try to reconstruct Partition Table entry for the damaged partition entry.

Why partition boot sector is so important?

Because if recovery software finds it, all necessary parameters to reconstruct partition entry in the Partition Table are there.

What would happen if partition entry had been deleted then recreated with other parameters and re-formatted?

In this case, instead of the original partition entry we would have a new one and everything would work fine except that later on we could recall that we had some important data on the original partition. If you've created MBR, Partition Table, Volume Sectors backup (for example, Active@ Partition Recovery and Active@ UNERASER (Unformat) can do it) before, you can virtually restore it back and look for your data (in case if it has not been overwritten with new data yet).
Some advanced recovery tools also have an ability to scan disk surface and try to reconstruct the previously deleted partition information from the pieces of left information (i.e. perform virtual partition recovery). However it is not guaranteed that you can recover something.

 

MBR is damaged

The Master Boot Record (MBR) will be created when you create the first partition on the hard disk. It is very important data structure on the disk. The Master Boot Record contains the Partition Table for the disk and a small amount of executable code for the boot start. The location is always the first sector on the disk.
The first 446 (0x1BE) bytes are MBR itself, the next 64 bytes are the Partition Table, the last two bytes in the sector are a signature word for the sector and are always 0x55AA.

For our disk layout we have MBR:

Physical Sector: Cyl 0, Side 0, Sector 1
000000000   33 C0 8E D0 BC 00 7C FB  50 07 50 1F FC BE 1B 7C   3AZ??.|uP.P.u?.|
000000010   BF 1B 06 50 57 B9 E5 01  F3 A4 CB BE BE 07 B1 04   ?..PW?a.o¤E??.±.
000000020   38 2C 7C 09 75 15 83 C6  10 E2 F5 CD 18 8B 14 8B   8,|.u.??.aoI.‹.‹
000000030   EE 83 C6 10 49 74 16 38  2C 74 F6 BE 10 07 4E AC   i??.It.8,to?..N¬
000000040   3C 00 74 FA BB 07 00 B4  0E CD 10 EB F2 89 46 25   <.tu»..?.I.eo‰F%
000000050   96 8A 46 04 B4 06 3C 0E  74 11 B4 0B 3C 0C 74 05   –SF.?.<.t.?.<.t.
000000060   3A C4 75 2B 40 C6 46 25  06 75 24 BB AA 55 50 B4   :Au+@?F%.u$»?UP?
000000070   41 CD 13 58 72 16 81 FB  55 AA 75 10 F6 C1 01 74   AI.Xr.?uU?u.oA.t
000000080   0B 8A E0 88 56 24 C7 06  A1 06 EB 1E 88 66 04 BF   .Sa?V$C.?.e.?f.?
000000090   0A 00 B8 01 02 8B DC 33  C9 83 FF 05 7F 03 8B 4E   ..?..‹U3E?y..‹N
0000000A0   25 03 4E 02 CD 13 72 29  BE 46 07 81 3E FE 7D 55   %.N.I.r)?F.?>?}U
0000000B0   AA 74 5A 83 EF 05 7F DA  85 F6 75 83 BE 27 07 EB   ?tZ?i.U…ou??'.e
0000000C0   8A 98 91 52 99 03 46 08  13 56 0A E8 12 00 5A EB   S?‘R™.F..V.e..Ze
0000000D0   D5 4F 74 E4 33 C0 CD 13  EB B8 00 00 00 00 00 00   OOta3AI.e?......
0000000E0   56 33 F6 56 56 52 50 06  53 51 BE 10 00 56 8B F4   V3oVVRP.SQ?..V‹o
0000000F0   50 52 B8 00 42 8A 56 24  CD 13 5A 58 8D 64 10 72   PR?.BSV$I.ZX?d.r
000000100   0A 40 75 01 42 80 C7 02  E2 F7 F8 5E C3 EB 74 49   .@u.B€C.a?o^AetI
000000110   6E 76 61 6C 69 64 20 70  61 72 74 69 74 69 6F 6E   nvalid partition
000000120   20 74 61 62 6C 65 00 45  72 72 6F 72 20 6C 6F 61    table.Error loa
000000130   64 69 6E 67 20 6F 70 65  72 61 74 69 6E 67 20 73   ding operating s
000000140   79 73 74 65 6D 00 4D 69  73 73 69 6E 67 20 6F 70   ystem.Missing op
000000150   65 72 61 74 69 6E 67 20  73 79 73 74 65 6D 00 00   erating system..
000000160   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000170   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000180   00 00 00 8B FC 1E 57 8B  F5 CB 00 00 00 00 00 00   ...‹u.W‹oE......
000000190   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
0000001A0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
0000001B0   00 00 00 00 00 00 00 00  A6 34 1F BA 00 00 80 01   ........¦4.?..€.
0000001C0   01 00 07 FE 7F 3E 3F 00  00 00 40 32 4E 00 00 00   ...?>?...@2N...
0000001D0   41 3F 06 FE 7F 64 7F 32  4E 00 A6 50 09 00 00 00   A?.?d2N.¦P....
0000001E0   41 65 0F FE BF 4A 25 83  57 00 66 61 38 00 00 00   Ae.??J%?W.fa8...
0000001F0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 AA   ..............U?

What will happen if the first sector has been damaged (by virus, for example)?

Lets overwrite the first 16 bytes with zeros.

000000000   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
000000010   BF 1B 06 50 57 B9 E5 01  F3 A4 CB BE BE 07 B1 04   ?..PW?a.o¤E??.±.

When we try to boot after hardware testing procedures, we see just blank screen without any messages. It means the piece of code at the beginning of the MBR could not be executed properly. That’s why even error messages could not be displayed. However, if we boot from the floppy, we can see FAT partition, files on it and we are able to perform standard operations like file copy, program execution... It happens because in our example only part of the MBR has been damaged which does not allow the system to boot properly. However, the partition table is safe and we can access our drives when we boot from the operating system installed on the other drive.

What will happen if sector signature (last word 0x55AA) has been removed or damaged?

Lets write zeros to the location of sector signature.

Physical Sector: Cyl 0, Side 0, Sector 1
0000001E0   41 65 0F FE BF 4A 25 83  57 00 66 61 38 00 00 00   Ae.??J%?W.fa8...
0000001F0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................

 When we try to boot now, we see an error message like "Operating System not found".

Thus the first thing if computer does not boot is to run Disk Viewer and check the first physical sector on HDD, whether it looks like valid MBR or not:

• check, may be it's filled up with zeros or any other single character
• check whether error messages (like you can see above "Invalid partition table"...) are present or not
• check whether disk signature (0x55AA) is present or not

The simplest way to repair or re-create MBR is to run Microsoft's standard utility called FDISK with a parameter /MBR, like

A:\> FDISK.EXE  /MBR

FDISK is a standard utility included in MS-DOS, Windows 95, 98, ME.

If you have Windows NT / 2000 / XP, you can boot from startup floppy disks or CD-ROM, choose repair option during setup, and run Recovery Console. When you are logged on, you can run FIXMBR command to fix MBR.

Also you can use third party MBR recovery software or if you've created MBR backup, restore it from there (Active@ Partition Recovery has such capabilities).
 
What will happen if the first sector is bad/unreadable?

Most likely we'll get the same black screen, which we got when trying to boot. When you try to read it using Disk Viewer/Editor you should get an error message saying that sector is unreadable. In this case recovery software is unable to help you to bring HDD back to the working condition, i.e. physical partition recovery is not possible. The only thing that can be done is to scan and search for partitions (i.e. perform virtual partition recovery), and in case if something is found - display them and give the user an opportunity to save important data to another location. Third party software, like Active@ File Recovery, will help you here.

Partition Recovery Concepts

For the machine to be able to start booting properly, the following conditions should apply:

• Master Boot Record (MBR) exists and is safe
• Partition Table exists and contains at least one active partition

If so, executable code in MBR selects an active partition and passes control there, thus it can start loading proper files (COMMAND.COM, NTLDR, ... ) depending on the file system type on that partition.

However, if these files are missing or corrupted then OS will be unbootable - remember the famous error "NTLDR is missing ..." ? In this case recovery software accesses this drive on the low level bypassing system boot (for example, if you boot from another HDD or bootable floppy) and will help you to see all other files and directories on the drive and allow you to copy to the safe place onto another drive.
For the partition/drive to be visible to the Operating System the following conditions should apply:

• Partition/Drive can be found via Partition Table
• Partition/Drive boot sector is safe

If so, OS can read partition/drive parameters and display drive in the list of the available drives. However, if the file system itself is damaged (Root, FAT area on FAT12/FAT16/FAT32, or system MFT records on NTFS) drive's content might not be displayed  and we might see errors like "MFT is corrupted", "Drive is invalid" ... In this case you have less chances to restore your data in compare to the case where OS is not bootable due to the missing or corrupted system files, however recovery software usually uses some tricks to display may be not all but some of the entries that are still safe and allow you to save your data to another location.

Under "Partition recovery" we mean two things:

1. "Physical partition recovery". The goal is to find out the problem and write some information to the proper place on HDD and after that partition becomes visible to OS again. You can do it manually using Disk Editors and some guidelines or use recovery software, designed for this purpose.
2. "Virtual partition recovery". The goal is to determine the critical parameters of the deleted/damaged/overwritten partition and after that enable to scan it and display its content. This approach can be applied in some cases when physical partition recovery is not possible (for example, partition boot sector is dead) and is commonly used by recovery software. It's very hard (almost impossible) to implement it manually.

Lets consider the topics, related to the recovery of partitions in common, not specific to the particular file system. We have the following cases:

• MBR is damaged
• Partition is deleted or Partition Table is damaged
• Partition Boot Sector is damaged
• Missing or Corrupted System Files

source:ntfs.com

NTFS Master File Table (MFT)

Each file on an NTFS volume is represented by a record in a special file called the master file table (MFT). NTFS reserves the first 16 records of the table for special information. The first record of this table describes the master file table itself, followed by a MFT mirror record. If the first MFT record is corrupted, NTFS reads the second record to find the MFT mirror file, whose first record is identical to the first record of the MFT. The locations of the data segments for both the MFT and MFT mirror file are recorded in the boot sector. 

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.

Table 5-4 Metadata Stored in the Master File Table

System File	File Name	MFT Record	Purpose of the File
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.
Quota management file	$Quota	24	Contains user assigned quota limits on the volume space.
Object Id file	$ObjId	25	Contains file object IDs.
Reparse point file	$Reparse	26	This file contains information about files and folders on the volume include reparse point data

MFT Structure

The master file table allocates a certain amount of space for each file record. The attributes of a file are written to the allocated space in the MFT. Small files and directories (typically 512 bytes or smaller), such as the file illustrated in next figure, can entirely be contained within the master file table record.

MFT Record for a Small File or Directory:

This design makes file access very fast. Consider, for example, the FAT file system, which uses a file allocation table to list the names and addresses of each file. FAT directory entries contain an index into the file allocation table. When you want to view a file, FAT first reads the file allocation table and assures that it exists. Then FAT retrieves the file by searching the chain of allocation units assigned to the file. With NTFS, as soon as you look up the file, it's there for you to use.
Directory records are housed within the master file table just like file records. Instead of data, directories contain index information. Small directory records reside entirely within the MFT structure. Large directories are organized into B-trees, having records with pointers to external clusters containing directory entries that could not be contained within the MFT structure.

Cross linked from ntfs.com

Partition Boot Sector

Table 5-1 describes the boot sector of a volume formatted with NTFS. When you format an NTFS volume, the format program allocates the first 16 sectors for the $Boot metadata file. First sector, in fact, is a boot sector with a "bootstrap" code and the following 15 sectors are the boot sector's IPL (initial program loader). To increase file system reliability the very last sector an NTFS partition contains a spare copy of the boot sector.
Table 5-1 NTFS Boot Sector

Byte Offset	Field Length	Field Name
0x00	3 bytes	Jump Instruction
0x03	LONGLONG	OEM ID
0x0B	25 bytes	BPB
0x24	48 bytes	Extended BPB
0x54	426 bytes	Bootstrap Code
0x01FE	WORD	End of Sector Marker

On NTFS volumes, the data fields that follow the BPB form an extended BPB. The data in these fields enables Ntldr (NT loader program) to find the master file table (MFT) during startup. On NTFS volumes, the MFT is not located in a predefined sector, as on FAT16 and FAT32 volumes. For this reason, the MFT can be moved if there is a bad sector in its normal location. However, if the data is corrupted, the MFT cannot be located, and Windows NT/2000 assumes that the volume has not been formatted.
The following example illustrates the boot sector of an NTFS volume formatted while running Windows 2000. The printout is formatted in three sections:

• Bytes 0x00- 0x0A are the jump instruction and the OEM ID (shown in bold print).
• Bytes 0x0B-0x53 are the BPB and the extended BPB.
• The remaining code is the bootstrap code and the end of sector marker (shown in bold print).

Physical Sector:Cyl 0, Side 1, Sector 1 
      00000000:EB 52 90 4E 54 46 53 20 -20 20 20 00 02 08 00 00 .R.NTFS ........ 
      00000010:00 00 00 00 00 F8 00 00 -3F 00 FF 00 3F 00 00 00 ........?...?... 
      00000020:00 00 00 00 80 00 80 00 -4A F5 7F 00 00 00 00 00 ........J....... 
      00000030:04 00 00 00 00 00 00 00 -54 FF 07 00 00 00 00 00 ........T....... 
      00000040:F6 00 00 00 01 00 00 00 -14 A5 1B 74 C9 1B 74 1C ...........t..t. 
      00000050:00 00 00 00 FA 33 C0 8E -D0 BC 00 7C FB B8 C0 07 .....3.....|.... 
      00000060:8E D8 E8 16 00 B8 00 0D -8E C0 33 DB C6 06 0E 00 ..........3..... 
      00000070:10 E8 53 00 68 00 0D 68 -6A 02 CB 8A 16 24 00 B4 ..S.h..hj....$.. 
      00000080:08 CD 13 73 05 B9 FF FF -8A F1 66 0F B6 C6 40 66 ...s......f...@f 
      00000090:0F B6 D1 80 E2 3F F7 E2 -86 CD C0 ED 06 41 66 0F .....?.......Af. 
      000000A0:B7 C9 66 F7 E1 66 A3 20 -00 C3 B4 41 BB AA 55 8A ..f..f....A..U. 
      000000B0:16 24 00 CD 13 72 0F 81 -FB 55 AA 75 09 F6 C1 01 .$...r...U.u.... 
      000000C0:74 04 FE 06 14 00 C3 66 -60 1E 06 66 A1 10 00 66 t......f`..f...f 
      000000D0:03 06 1C 00 66 3B 06 20 -00 0F 82 3A 00 1E 66 6A ....f;....:..fj 
      000000E0:00 66 50 06 53 66 68 10 -00 01 00 80 3E 14 00 00 .fP.Sfh.....>... 
      000000F0:0F 85 0C 00 E8 B3 FF 80 -3E 14 00 00 0F 84 61 00 ........>.....a. 
      00000100:B4 42 8A 16 24 00 16 1F -8B F4 CD 13 66 58 5B 07 .B..$......fX [.. 
      00000110:66 58 66 58 1F EB 2D 66 -33 D2 66 0F B7 0E 18 00 fXfX.-f3.f...... 
      00000120:66 F7 F1 FE C2 8A CA 66 -8B D0 66 C1 EA 10 F7 36 f......f..f....6
      00000130:1A 00 86 D6 8A 16 24 00 -8A E8 C0 E4 06 0A CC B8 ......$......... 
      00000140:01 02 CD 13 0F 82 19 00 -8C C0 05 20 00 8E C0 66 ..............f 
      00000150:FF 06 10 00 FF 0E 0E 00 -0F 85 6F FF 07 1F 66 61 ..........o...fa 
      00000160:C3 A0 F8 01 E8 09 00 A0 -FB 01 E8 03 00 FB EB FE ................ 
      00000170:B4 01 8B F0 AC 3C 00 74 -09 B4 0E BB 07 00 CD 10 .....<.t........ 
      00000180:EB F2 C3 0D 0A 41 20 64 -69 73 6B 20 72 65 61 64 .....A disk read 
      00000190:20 65 72 72 6F 72 20 6F -63 63 75 72 72 65 64 00 error occurred. 
      000001A0:0D 0A 4E 54 4C 44 52 20 -69 73 20 6D 69 73 73 69 ..NTLDR is missi 
      000001B0:6E 67 00 0D 0A 4E 54 4C -44 52 20 69 73 20 63 6F ng...NTLDR is co 
      000001C0:6D 70 72 65 73 73 65 64 -00 0D 0A 50 72 65 73 73 mpressed...Press 
      000001D0:20 43 74 72 6C 2B 41 6C -74 2B 44 65 6C 20 74 6F Ctrl+Alt+Del to 
      000001E0:20 72 65 73 74 61 72 74 -0D 0A 00 00 00 00 00 00 restart........
      000001F0:00 00 00 00 00 00 00 00 -83 A0 B3 C9 00 00 55 AA ..............U. 

The following table describes the fields in the BPB and the extended BPB on NTFS volumes. The fields starting at 0x0B, 0x0D, 0x15, 0x18, 0x1A, and 0x1C match those on FAT16 and FAT32 volumes. The sample values correspond to the data in this example.

Protecting the Boot Sector

Because a normally functioning system relies on the boot sector to access a volume, it is highly recommended that you run disk scanning tools such as Chkdsk regularly, as well as back up all of your data files to protect against data loss if you lose access to a volume.

source: ntfs.com