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DiskPatch Frequently Asked Questions & common problems and solutions

DiskPatch upgrade information

Trial version details

Interesting DiskPatch links

Getting started: rules and tutorials

How to initiate a support request

DiskPatch and USB

System displays "Invalid partition table" and then halts

System halts at "Verifying DMI pool" or displaying a black screen

Can DiskPatch recover a formatted disk (perform an Unformat) ?

Converting a Windows Dynamic disk (back) to a Basic disk

DiskPatch can't create state files or can't save Partition State Backups

I receive a memory warning or error during disk analysis

Running DiskPatch puts me back at the "A:>" prompt

Disk Partition State backups and other third party Partition management software

Extended Int13H (direct disk access) error codes

DiskPatch upgrade information
The latest version of DiskPatch is 4.0.300. Download and install the trial and use your license code to unlock full functionality.

Current DiskPatch 3 users can download the new version 4 and use their current license key to unlock the program.

There is NO upgrade path for DiskPatch 2 to DiskPatch 4; a new license must be purchased. Also, there is no upgrade path for any version of DiskPatch older than version 2; a new license must be purchased.

Never post any license details in the support forum.

Trial version details
The DiskPatch setup installs the complete version of DiskPatch, but you will need a license key to unlock full functionality. You will not have to download and re-install another program after you have bought the license key, simply enter the key and DiskPatch is ready for use.

If you run DiskPatch without a license key, the program will run in 'Trial-Mode': all features are enabled and accessible, but DiskPatch will not write any changes to the disk.
The Trial mode allows you to diagnose the problem disk and create the Support Analysis log. This log will give us the information we need to help you on your way to a speedy recovery. Installing the Trial version, creating the log and letting us take a look is the perfect way to get started; it's safe and completely free of charge.

Interesting DiskPatch links

Online manual
Download manual (for offline viewing and printing)
Product page
Download the latest version
DiskPatch quickstart guides
Buy DiskPatch

Getting started: rules and tutorials
When confronted with a data recovery situation these 4 golden rules apply (until you know exactly what you're dealing with):
  • DO NOT run 'chkdsk' or 'scandisk' or any other partition repair utility
  • DO NOT use the Windows recovery console commands 'fixmbr' or 'fixboot'
  • DO NOT attempt to recreate a deleted partition with 'Fdisk' or 'Disk Management'
  • DO NOT change the contents of the disk or partition that needs to be recovered

In a hurry to get going with DiskPatch? Need an illustrated guide to help you through a repair procedure? Use one of the following guides to help you get underway quickly:

Tutorial start page 
Creating the support analysis log and requesting support 
Repair or rebuild a partition table 
Repair or rebuild a NTFS boot sector 
Repair or rebuild a FAT boot sector 
Run a disk surface scan 
Wipe or low-level format a disk or partition 
Clone a disk for recovery purposes 
How to use the Disk editor 
Create or Restore partition state backups 
Set partition attributes 
Refresh the MBR boot code 

The most current DiskPatch manual can be found online here.

How to initiate a support request
Support is handled through our Support Forum.

Everything DiskPatch does is captured in a log file. Log files are created in the folder DPFILES. DiskPatch keeps a history of the 6 most recent log files, DP.LOG being the most recent, and DP.LO5 the oldest. Please note: if you have problems when saving log files (for instance when using a bootable CD/DVD), read more here.

DIY DataRecovery Support uses the DiskPatch log file to determine the scope of the problem at hand. The log file also enables support to give you accurate advice on how to perform the recovery procedure, should you need advice. When posting a new support request, please create a Support Analysis Log file and include this in your posting.

This walkthrough explains how to create a support analysis log file.

Please note that the log file should be accompanied by a description of the problem. The following rules apply:

  • We do not send attachments to free email accounts! If for any reason we need to send zipped executables, you must provide us with an email address capable of receiving zipped attachments larger than 1 Mb.
  • Include a thorough description of the actions that led to the problem. If you can, describe briefly what you think caused the problem.
  • Include a description of the running OS (Windows 9x / ME / NT / 200X / XP / Vista / Win7/8 or OS/2 or Linux etc.), including version information, Service Pack levels and the file-system (FAT, NTFS, etc.) in use.
  • When you are dealing with MBR, partition table and boot sector related issues, please create a DiskPatch SUPPORT ANALYSIS LOGFILE. Typical symptoms of such issues are entire drives and partitions that can't be accessed. If you have already performed repairs, include the DiskPatch log file(s) in the support request.
  • Include relevant information such as descriptions of symptoms and actual (error) messages that are displayed when trying to access the data, file system etc. If you have lost partitions, describe the partitions as they were before the problems occurred.
  • When relevant, include hardware information (internal/external controller, array information etc.) if you think it has any bearing on the problem at hand.

If you have already performed a repair but need additional assistance, please include the contents of the most relevant log file. In general this will be the most recent log file (DP.LOG), but it may also be an older log file if you have restarted DiskPatch.

Please do not include irrelevant information or files (such as the state files or old log files) unless we specifically ask for them.

Downloading and using the DiskPatch Trial version, posting the log file and asking for our recommendations is all free of charge.

If you prefer email you can send your support request to DIY DataRecovery support.

Download DiskPatch here.

DiskPatch and USB
Most current PCs allow access to USB disks (and sticks or keys) when running DOS, so DiskPatch should be able to access these disks. In most cases you need to enable a BIOS setting that enables access to USB disks from DOS; this setting will be named "USB legacy support" or something similar. Consult your BIOS manual for more information on this. On older PCs DiskPatch will usually not be able to identify USB connected disks, but there are ways to get DiskPatch to work with these disks.

1. "Legacy USB devices"

In many PC BIOS versions there is an option for enabling "legacy USB". Enabling this option might allow DOS oriented applications (such as DiskPatch) to access a USB disk without the need for additional drivers. The only way to see if this works is to try: enable BIOS option "legacy USB" and then start the PC from the DiskPatch boot disk. Open the "select disk" menu and see if the disk shows up.

2. modern day BIOS versions

Most modern BIOS versions are capable of booting from a USB device. If so, it's more than likely that the BIOS can identify a USB device as a disk at boot time, so DiskPatch should have no trouble accessing this disk; there should be no need for additional drivers or tweaking. It may be necessary to enable "legacy USB" in the BIOS.

3. older BIOS versions

If the BIOS does not recognize the USB disk at all from DOS (i.e. DiskPatch does not see the disk) there's a final option that might work: use DOS USB drivers. Adding these drivers to the DiskPatch boot disk may enable DiskPatch to work with the disks. This can be done as follows:

Download the drivers here (*). Extract the archive to the DiskPatch boot disk, place the contents of the zip file in the root directory of the disk. You will need to add the USB drivers to the config.sys file, check the included readme.txt file for details.

Start the PC using the modified DiskPatch boot disk. USB support will be loaded automatically. Loading the drivers may take some time so be patient when starting from the modified bootable disk. Also, make sure all USB devices are connected before starting from the disk.
Do NOT use USB drivers when booting the PC with a bootable USB disk.

Things to keep in mind:

  • accessing USB connected devices from DOS is slow.
  • if the disk that is selected has no MBR, DiskPatch may ask questions about the disk's geometry (how many heads and sectors/track): some BIOS versions assign geometry based on what is in the MBR, so if no MBR is found strange geometry values are assigned. Contact support when this happens.
  • there's a chance that the USB drivers won't work with the Freedos version that is included on the DiskPatch boot disk (the PC might lock up after the USB driver messages). If this happens you will need to create your own DOS boot disk.
    Contact support if you require assistance in this situation.

If USB support from DOS (using drivers or any other means) works, disks are not the only devices that can be accessed from DOS: anything that presents itself as a disk can be accessed. Think USB sticks, USB connected digital camera's etc. If these devices have partitions that have data on it, you can access them (and repair them if needed) using the described methods.

(*) These drivers are not supported or created by DIY DataRecovery. Use them at your own risk.

System displays "Invalid partition table" and then halts
Damage to the MBR and/or the partition table typically affects the boot process, and symptoms occurring during the boot process may help reveal the nature of the problem.

Symptom: system does not boot - Displays "Invalid Partition Table" message

Cause: the system encountered an 'illegal' condition in the MBR partition table. An error is displayed if the following conditions are NOT met:

  • One partition is flagged active [*]
  • None of the partitions is flagged active

[*] - If a partition is flagged active, it will be selected as the partition that will start the operating system.


If MBR damage is limited to one of the conditions mentioned above not being met, the DiskPatch 'Change partition attributes' feature can help you resolve this: simply make sure that no more than one partition at the time is active.

If damage to the MBR is more extensive then use DiskPatch to:

System halts at "Verifying DMI pool" or displaying a black screen
Damage to the MBR and/or the partition table typically affects the boot process, and symptoms occurring during the boot process may help reveal the nature of the problem.

Symptom: system does not boot - system halts with a black screen or displays "Verifying DMI pool data" ... (actual message depends on system BIOS manufacturer and BIOS revision).

Cause: the system is in a loop and is unable to print a relevant error message to the screen. The screen will turn/stay black or the last message from the system BIOS remains visible.
Several things may cause this behavior:

  • The partition table is corrupt and the system finds unexpected values in the boot flag field in the partition table (should be decimal 0 or 128).
  • A partition entry points to an extended partition, which in turn points back to the MBR rather than to a next logical partition. The result is an eternal loop.


DiskPatch can resolve both problems by rebuilding a valid partition table. If the issue is caused by an extended partition pointing back to the MBR, MS-DOS and MS-DOS based operating systems such as Windows 9x and ME will fail to boot. As a result you can not start DiskPatch when it is run from MS-DOS. The FreeDOS version included with DiskPatch will allow you to boot and run DiskPatch.

Can DiskPatch recover a formatted disk (perform an Unformat) ?
No, DiskPatch attempts to repair the MBR (Master Boot Record), partition tables, boot sectors and File Allocation Tables (FATs). When a volume is formatted all these structures are (partially) newly created, overwriting or destroying the previous structures. When formatting has finished these structures are all intact, i.e. they don't need to be repaired since they've just been created. As such DiskPatch can't repair anything in this scenario because after a format nothing is actually broken. So performing an unformat is not possible using DiskPatch.

And for the record: we strongly advise against the use of 'unformatters', not because we do not offer such a program, but because there are good reasons to avoid such utilities; the results are often very poor and can not be reverted. If unformatting does not have the desired result or even makes the situation worse it also effectively decreases the chances of successfully using other file recovery software.

NEVER use unformatting software to recover data!

Converting a Windows Dynamic disk (back) to a Basic disk
DiskPatch is NOT a dynamic-to-basic disk converter. Even though the process of recovering lost volumes on a dynamic disk may result in the disk becoming a basic disk, DiskPatch was never designed as a dynamic-to-basic disk converter.

BUT, yes, it is possible (under certain conditions) to convert a dynamic disk back to a basic disk:

If the disk was 'basic' at the time it was partitioned there's a good chance that simply rebuilding the partition tables on a 'dynamic' disk (using DiskPatch) will turn the disk into a 'basic' disk once again. Obviously, the disk has to contain only 'simple volumes': if spanning (or any other Windows based scheme that uses more than 1 disk to house volumes) was used, it is NOT possible to convert the disk(s) back to a 'basic' disk.

If you decide to give this a try we suggest the following procedure (read the DiskPatch manual for details on the specific tasks):

  • create a backup of the partition structures
  • rebuild the partition tables
  • test the result. Make sure nothing on the disk is changed (no chkdsk, defrag etc.)
  • if the results are good: start using the disk as a basic disk. if the results are bad: restore the backup you made earlier

Again, DiskPatch was not specifically designed to convert dynamic disks to basic disks; you try this at your own risk.

More information can be found in the DiskPatch manual.

DiskPatch can't create state files or can't save Partition State Backups
If you can not create a partition table backup, or if saving state files is prohibited, it's most likely to be caused by this:

DiskPatch uses one specific sector on a disk to save its bookkeeping. This sector is in a region of the disk that is not used by any operating system. The LBA address for this sector is 29. Before using this sector DiskPatch makes sure that the sector is empty. If it is not, DiskPatch plays it safe and will not use the sector (just in case something important is in there). Since a number of functions depend on the use of sector 29, a few thing won't be possible if sector 29 is not claimed by DiskPatch:

  • saving a state file after an analysis scan
  • creating backups of partition tables and boot sectors

To make DiskPatch use sector 29 (and to be able to use all functions) you would have to clear sector 29. You may however first wish to check what's in there, just in case. You can use the Disk editor to view the sector's contents. Press 'del' to wipe the contents of the sector. If you wish you can submit a log to DIY DataRecovery support with the contents of the sector so we can determine for you if it's safe to clear sector 29.

To have us look at the contents of sector 29 and advise you on whether it's safe to wipe, do the following:

  • start DiskPatch
  • select the disk
  • start the disk editor (from the utilities menu)
  • press F4, enter '29'
  • press F10, select 'dump sector to log'
  • exit DiskPatch
  • send the resulting log file along with your support request

To simply clear the sector so DiskPatch can use it, do the following:

  • start DiskPatch
  • select the disk
  • start the disk editor (from the utilities menu)
  • press F4, enter '29'
  • press 'del' to clear the sector
  • perform the steps above for each disk
  • restart DiskPatch

DiskPatch can now use sector 29.

This method of clearing sector 29 (using the disk editor) can only be used with the registered version of DiskPatch. If you have a trial version and wish to clear sector 29, do the following:

  • start from the DiskPatch boot disk
  • exit the menu, you should now see the command prompt
  • on the command prompt type 'DP.EXE /inz' (without the quotes)
  • DiskPatch will clear sector 29 for all disks in the system

Obviously, this method can also be used when using the registered version of DiskPatch.

I receive a memory warning or error during disk analysis

There are a number of possible causes for this. The included Freedos may be the problem, or the disk you're scanning has an exceptionally high number of partitions on it. Send the DiskPatch log file to our support department, we can then determine what the problem is and hopefully address it.
Follow these guidelines when submitting a request for support.

Running DiskPatch puts me back at the "A:>" prompt

The most likely cause for this is an incompatibility between Freedos (which is included in the DiskPatch distribution) and your computer. You will have to create a boot disk yourself and put DiskPatch on it. Contact support if you require assistance in this situation.

Disk Partition State backups and other third party Partition management software
Using DiskPatch in conjunction with Acronis TrueImage Secure Zone, PowerQuest DriveImage, Symantec's v2i Protector, Ghost/DriveImage or Goback.

Aforementioned programs all have in common that they write information to track 0 which, apart from LBA sector 0 (the MBR), is normally empty. Some also modify the MBR partition tables and boot code. DiskPatch does not alter any already existing information for storing disk layout backups and will therefore not cause incompatibility issues due to non standard partition tables or MBR boot code.

Sectors in track 0 that DiskPatch uses: DiskPatch first checks if LBA sector 29 is available, and if so, it will create its 'admi-sector' there. If this sector is not available (bad or in use) DiskPatch can run without the admi-sector but certain features will not be available, for example state file creation. When sector 29 is available DiskPatch will always use it unless DiskPatch is started in Forensic mode. The MBR and boot sector backups that DiskPatch creates are saved to the sectors following the admi-sector, sectors 30 to 34. These are checked to see if they are free for use. If they're not, the backup does not proceed.
So, in short:

  • sector 29 : DiskPatch administration
  • sector 30 : MBR backup
  • sector 31 - 34 : up to 4 boot sector backups for all primary partitions

DiskPatch and PowerQuest's DriveImage virtual floppy technology: The virtual floppies require some free space in track 0. The algorithms installing the virtual floppy are intelligent enough to determine if sectors are in use or not and will simply continue looking for free sectors. DiskPatch backups are not overwritten in the process. If DiskPatch can't create its disk layout backup ('target sector(s) not available'): clean track 0 with MBRtool. Then create the DiskPatch disk layout backups. If you now run DriveImage the virtual floppy will be installed without overwriting the DiskPatch disk layout backups. The PowerQuest virtual floppy also alters the MBR boot code, but only during the reboot; original boot code is written back as soon as the virtual floppy finished booting.

DiskPatch and v2i (Ghost, DriveImage, V2i Protector): Unlike older DriveImage versions the V2i driven tools do not use a virtual floppy. If DiskPatch is unable to store its backup due to lack of target sectors, clean track 0 using MBRtool.

DiskPatch and Goback: Goback replaces system descriptors in the MBR partition table with its own (type 44h), and replaces the boot code. As a result DiskPatch is unable to locate primary partitions or the extended partitions, and a disk layout backup can not be made while Goback is 'active'. You can disable Goback and then create a disk layout backup.

DiskPatch and TrueImage Secure Zone: This is not yet investigated and is not documented by Acronis. The fact that pressing F11 during boot up results in a 'Recovery Manager' from the Secure Zone suggests that the MBR boot code is altered when Secure Zone is installed. Acronis itself advises against the use of Secure Zone and Startup Manager if other tools are installed that alter the MBR (like Goback).

DIY DataRecovery recommendation: Avoid using software that permanently alters the MBR boot code or partition tables, and avoid using features in software that require changes to MBR boot code or partition tables. For example, TrueImage is a great tool, however avoid activating the Secure Zone and Startup Recovery Manager features.

All mentioned 3rd party products do not prohibit recovering lost, deleted or damaged partitions using DiskPatch! However, you may need to reinstall or re-enable features of the 3rd party products after recovering partitions with DiskPatch.

Extended Int13H (direct disk access) error codes
In general this category of errors indicates (serious) hardware problems that can not be resolved using software; as a result the hard disk does not respond well (or not at all) when read from or written to.

These errors are intercepted by DiskPatch (if they occur) and are saved in the log. DiskPatch will warn you if certain errors are a threat or may otherwise require attention.

When these errors occur, if the hard disk is still detected in the BIOS, you should clone the disk. When you run into a situation like this and don't know how to proceed, contact support. Follow these guidelines when submitting a request for support.

Some of the following errors can not be bypassed, while others, for example error 80h (time-out), may be resolved by trying to read the sector several times.

Return Code & Description

  • 01h Invalid function in AH or invalid parameter
  • 02h Address mark not found
  • 03h Disk is write-protected
  • 04h Sector not found / Read error
  • 05h Reset failed
  • 07h Drive parameter activity failed
  • 08h DMA overrun
  • 09h Data boundary error
  • 0Ah Bad sector detected
  • 0Bh Bad track detected
  • 0Ch Unsupported track or invalid media
  • 0Dh Invalid number of sectors on format
  • 0Eh Control data address mark detected
  • 0Fh DMA arbitration level out of range
  • 10h Uncorrectable CRC or ECC error on read
  • 11h Data ECC corrected
  • 20h Controller failure
  • 32h Incorrect drive type stored in CMOS
  • 40h Seek failed
  • 80h Timeout
  • AAh Drive not ready
  • BBh Undefined error
  • CCh Write fault
  • HEh Status register error
  • FFh Sense operation failed
  • ?? Unexpected int13h error

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