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ddrutility.txt
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ddrutility
1 Introduction
2 ddru_findbad
3 ddru_ntfsbitmap
4 ddru_ntfsfindbad
5 ddru_diskutility
6 Important Notes
7 Reporting Bugs
Index
ddrutility
**********
This manual is for ddrutility (version 2.8.1, 13 October 2022).
This documentation was created and is maintained as a texinfo file,
and translated to markdown for use on the ddrutiltiy Sourceforge Wiki
page. The navigation does not work on the Wiki page. You can download
help.html from the files section and open it with a web browser and the
navigation will work.
1 Introduction
**************
Ddrutility is a linux based set of utilities designed to assist with
data recovery, specifically as a supplement to GNU ddrescue. Each
utility has its own version number followed by the date last updated.
Note that most if not all of these utilities need to be ran as root. It
contains the following programs:
'ddru_findbad'
'ddru_ntfsbitmap'
'ddru_ntfsfindbad'
'ddru_diskutility'
'ddru_findbad' is actually the original ddrutility version 1.6. None
of its functionality has changed; only the name and documentation have
been changed, and some bug fixes and improvements have been done. It is
a bash script that will try to find which files are related to bad
sectors in a ddrescue log file. It relies on 3rd party utilities for
its functions. It may not work on all systems. It can be slow, and can
be very slow if not unusable if there are a lot of bad sectors in the
list (it does not work well with a large error size). While I will fix
any bugs found in it, I do not plan on performing any major updates or
improvements of its functionality. It is possible (hopeful) that I may
create new utilities to replace it (or parts of it) in the future.
These utilities would not rely on 3rd party functions, and would be
faster.
'ddru_ntfsbitmap' is a utility to extract the bitmap file from a NTFS
partition, and then process it and create a domain file to be used with
ddrescue. This would allow for only recovering the used portion of the
partition, and not spending time reading unused and unneeded data.
'ddru_ntfsfindbad' is a utility for NTFS partitions to find which
files are related to bad sectors in a ddrescue log file. You should use
this for NTFS partitions in place of the original ddru_findbad, as it is
MUCH faster than the original ddru_findbad, gives more useful output,
and does NOT require any 3rd party utilities. It will also do the best
it can to work with a damaged file system (and even give you an idea of
how damaged).
'ddru_diskutility' is an advanced LINUX ONLY utility that can perform
several different functions on a disk, using some direct pass-through
disk commands. Current functions include device inquiry, sector reads,
and read long commands. It is meant for advanced users.
2 ddru_findbad
**************
'ddru_findbad' is meant to be a compliment to gnuddrescue. It finds
which files are related to the bad sectors. It will also work with a
home made file of a bad sector list (see LOGFILE below). Note that
ddru_findbad may not work on a mounted drive or image.
If you performed a rescue that had some leftover bad sectors, but the
file system seems ok and you are wondering what might still be damaged
by the unrecovered sectors, then this program is for you. The
filesystem of the target must be intact enough for ddru_findbad to work.
If you are unable to mount the target and view its directory, then
ddrutility probably won't work and will just give errors. In this case
you may have to run some sort of repair tools on the target first and
hope that the filesystem can be repaired to a working state. Note that
any repair tool ran on the target could possibly cause ddru_findbad to
have inaccurate results. It is recommended that you always make an
extra copy of the recovered copy and work with that copy.
'ddru_findbad' is not meant to be run on the drive that actually has
the bad sectors. It is meant to be ran against a recovered copy of the
drive. FAT and HFS+ will fail if ran against the actual drive, as ifind
seems to feel the need to actually read the sectors in question. NTFS
and EXT seem to be processed without trying to read the sectors in
question, however understand that they still will be trying to read the
file table (which could have bad sectors) to get results.
'ddru_findbad' must be run as root (sudo).
'ddru_findbad' works on NTFS, EXT2/3/4, FAT16/32, and HFS+ file
systems (note that EXT4 will report as EXT3).
'ddru_findbad' requires sleuthkit to be installed for normal
operation. Sleuthkit is not included as standard in current Ubuntu
versions. (sudo apt-get install sleuthkit)
'ddru_findbad' requires ntfs-3g to be installed for NTFS support. If
it is not available then NTFS partitions will not be able to be
processed, and errors may be produced if trying to do so. Ntfs-3g seems
to be included in current Ubuntu versions. (sudo apt-get install
ntfs-3g)
'ddru_findbad' requires GNU fdisk to be installed to be able to
process GPT partitioned disks. If GNU fdisk is not available, then it
will use fdisk, but it will not be able to process GPT partitions and
may produce errors if trying to do so. GNU fdisk is not included as
standard in current Ubuntu versions. (sudo apt-get install gnu-fdisk)
Ubuntu Rescue Remix contains the above requirements, so it should run
on the live cd.
'ddru_findbad' will work on a whole drive recovery, or a single
partition recovery. It will work with a target device or image file.
Results are left in 4 main output files. Results_summary is a
condensed sorted summary file, and is probably the most useful output.
Results_list is the main output file. It contains information about
every sector processed with one line per sector. It is designed to be
easily processed to obtain desired final results (such as the summary
file). Results_info contains information about the partition table and
file system(s) and can be expanded with the moreinfo option.
Results_debug is mostly for troubleshooting purposes and most error
messages are sent to it. If you request help for any problems with
ddru_findbad I may ask for these 4 files.
'ddru_findbad' makes several temporary files in the directory that it
is run from. It deletes them when finished. Do not mount the target
and run ddru_findbad from within the target, as that would cause writing
to the target and you probably don't want that!
'ddru_findbad' does not knowingly write or alter any data on the
target drive and does not require the file system of the target to be
mounted. However, it makes calls to different 3rd party tools which
SHOULDN'T do any writing for what they are, but this has not been
verified.
Some errors or warnings may appear on screen when running. Don't
panic, some errors can be normal, as long as there is a good output. I
have tried to eliminate all the errors that I have found, but I cannot
test all possibilities. Most error messages are sent to results_debug.
If you question the error, please feel to email or post on the homepage
so that I can determine if it is something I should work on.
The format for running ddru_findbad is:
ddru_findbad TARGET LOGFILE [OPTIONS]
Where:
TARGET
The drive or partition if using a device (/dev/hda), or the name
(and full path if not in the current directory) of the image file
(/media/mydrive/image.dd). The target should be a copy or image of
the original drive with bad sectors. It should not be the actual
drive with bad sectors! If you should so choose to run it on the
actual drive for some reason, note that FAT and HFS+ will not
process with actual bad sectors.
LOGFILE
The logfile from ddrescue. It can alternatively be a file
containing a list of the bad sectors, one sector number per line
with no other text in the file. The sector file can also contain
bad sector ranges, with two sector numbers per line separated by a
space, being the first and last sector of the range. Note that the
sectors are in relation to either the whole disk or a single
partition, which depends on what the target is.
ddru_findbad supports the following options:
'-h'
'--help'
Print an informative help message describing the options and exit.
'-v'
'--version'
Print the version number and exit.
'-o FILE'
'--output FILE'
The base name that will be at the beginning of the multiple results
files. The default is "results". The different output files will
have extensions added to them, for example results_summary,
results_list, etc...
'-w SECONDS'
'--loopwait SECONDS'
The number of seconds to wait before doing loop commands. You
shouldn't have to change this. It is only used with image files.
The default is 2. Increase this if you get loop errors such as
device busy.
'-s BYTES'
'--sectorsize BYTES'
The sector size in bytes of the target drive or image. The default
is 512. Note that only a sector size of 512 has been tested, as I
don't have any drives of a different sector size to test.
'-a'
'--autooff'
Turns off automatic finding of partition types, and allows the user
to manually select what type the partition is for every partition.
It also gives the option to skip partitions. This could be useful
if for some reason the program is unable to properly find the
partition type, or you have multiple partitions and only want to
process one of them. The user will be prompted for every partition
on what to do. This choice will follow the processing of the
logfile, and if you choose to process a partition and there are
more after it, you will be prompted again after the current
partition is done processing.
'-m'
'--moreinfo'
Will add what could be considered an insane amount of (mostly)
useless data from fsstat and fls to the results_info file. Note
that at this time fls does not work right on EXT4 (sleuthkit
currently only supports ext2/3). If the file system is large,
moreinfo could cause the results_info file to get very big, and
could add a considerable (or insane) amount of processing time.
Only for advanced users, use this if you understand what output
fsstat and fls give.
'-e'
'--extraoutput'
Will produce more types of output files. The processing for this
is not very efficient at this time (it is actually horrible). If
there are a lot of bad sectors, this could take a considerable (or
insane) amount of processing time. If the quick or quickntfs
option is enabled then extraout will process much faster.
Currently available with the EXTRAOUT option: Results_bysector
lists the bad sector groups with the files in each group.
'-q'
'--quick'
Only processes the first and last sector of each group. This
allows for a much faster first run so you can get an idea of what
files are involved. May provide more useful output with the
EXTRAOUT option to get the results_bysector output. If the first
and last sector of a group show the same file then it could be
assumed that all the sectors in between are the same (assume at
your own risk). This is most efficient if there are large sized
groups of bad sectors. If most of the bad sectors are in very
small groups or individual sectors then this is not efficient and
will take nearly as long as a normal run.
'-Q'
'--quickntfs'
The same as quick, except it processes NTFS partitions extra
special. It uses the ability of ntfscluster to rapidly check
groups of sectors at once. This can very quickly produce a FULL
list of files related to bad sectors for NTFS partitions, instead
of of just checking the first and last sector of a group. As with
quick, it is still most efficient with large sector groups.
Results for NTFS partitions will not end up in the results_list
file, only in results_summary (and in results_bysector if the extra
option is used).
EXAMPLES:
If your ddrescue command was:
ddrescue /dev/sda1 rescued_image rescued_logfile
Then the ddru_findbad command would be:
ddru_findbad rescued_image rescued_logfile
If your ddrescue command was:
ddrescue /dev/sda /dev/sdb rescued_logfile
Then the ddru_findbad command would be:
ddru_findbad /dev/sdb rescued_logfile
NOTE: It is important that the source for ddru_findbad is the same as
the ddrescue outfile. Do not use /dev/sdb in the ddrescue command and
then /dev/sdb1 in the ddru_findbad command. This would cause very
inaccurate results.
It does not matter if the source for ddru_findbad is a disk or image, a
partition or a whole disk, as ddru_findbad will automatically process it
as long as it matches the format used to describe the ddrescue outfile.
3 ddru_ntfsbitmap
*****************
Ddru_ntfsbitmap is a utility that will extract the bitmap file from an
NTFS partition, and then create a rescue domain file to use with
ddrescue. This will allow recovering only the used portion of an NTFS
partition. Other normal cloning utilities (such as clonezilla, or at
least I think clonezilla uses something similar) use a similar method to
speed up the cloning process.
Ddru_ntfsbitmap requires that a version of ddrescue that includes
ddrescuelog is installed (ddrescue version 1.15 and up). It does not
make any other calls to 3rd party utilities.
The bitmap file is just a map of what clusters are used and free on
the partition. Consider the map as 0's and 1's, the 0's mean unused
clusters and the 1's mean used clusters. If any sectors of the bitmap
file are not readable by ddrescue (or were not tried), then they will be
filled with ones (FF) in the recovered bitmap output file. A section
that is all ones (FF) is considered as used clusters, and therefore the
corresponding data will be copied. Ddru_ntfsbitmap fills all bad (or
untried) bitmap sector(s) in the output file with ones to insure that no
needed data is missed during the recovery process, although it could
cause extra data to be copied (better safe than sorry).
Since the domain logfile that is created relies on the bitmap file
from the NFTS partition, it would be affected by any sort of corruption
that could have happened to the bitmap file caused when the filesystem
was running. So I can offer no guarantee that the results will be
accurate. All I can say is that the idea works, and the results SHOULD
be good. The safest way to make sure of the best possible data recovery
would be to continue on without the domain file after you got as far as
you could with it.
However, in addition to saving time, there COULD be another benefit
to not continuing on without the domain file in certain cases. If you
zero fill all the bad and untried areas of the target, then that could
possibly get rid of "garbage" data in the free space. This could
possibly make file recovery easier for programs that scan the whole disk
looking for files (such as photorec).
Ddru_ntfsbitmap will show the percentage of used vs free space of the
partition after processing the bitmap file, so you can get an idea of
how much time and effort you may be saving. You can also get this
number again later on by running ddrecuelog against the domain_logfile.
ddrescuelog -t domain_logfile
In the results, "rescued" will = used space that you are trying to
recover, and "non-tried" will = free space that you are ignoring. When
your rescue percentage reaches the percentage of used space, then you
should have recovered the needed data, except for any errors of course.
But you must have used the domain_logfile in all of the ddrescue
commands up to this point for this percentage match to be accurate.
After you reach this point and ddrescue exits, and you have done all the
rescuing of the used portion that you can or wish to (retries, no-split,
ect...), you could leave out the domain_logfile from the command and
continue to recover all of the remaining partition/drive if desired.
Ddru_ntfsbitmap uses ddrescue for all the reads and also creates
logfiles, so that you can run it as many times as you wish/need with
different ddrescue options on the same recovery attempt without unneeded
disk reads. However, you may need to use the -restart option to delete
all of the important files at the beginning of a new run so that there
are no issues caused by leftover files. If you used an incorrect
option, or there are leftover files from a previous rescue that you do
not realize, either case can cause weird results or errors, and this
option should clear that up and give you a fresh start without having to
manually delete the files. If you are getting an error or result that
doesn't make sense, try the -restart option.
While ddru_ntfsbitmap will only try to read any area once while
reading the bitmap file, the downside is that when you start the actual
rescue attempt, those areas will be read again. But this should be a
fairly small portion of the disk. For instance, at a standard 4k
cluster size, a 500GB drive bitmap file would be approximately 16MB
(0.003%).
Ddru_ntfsbitmap will create several output files in the directory
where it is ran. They are required if you need to run ddru_ntfsbitmap
again on the same drive with different ddrescue options to get the best
bitmap file recovery. They can be deleted if you aquired a successful
domain_logfile (but don't delete the domain_logfile until you have your
successful data recovery). They NEED TO BE DELETED OR SWITCHED TO A
DIFFERENT DIRECTORY if you are attempting a new rescue of a different
partition or a different disk. Also, if you do a command with the wrong
options that causes some error, you may want to also delete these files
and start over. The output files are as follows:
__BOOTSEC
This is the recovered partition boot sector (512 bytes). It is
needed to find the location of the MFT, along with the sector and
cluster size.
__BOOTSEC.LOG
This is the ddrescue logfile for the __bootsec file.
__MFTSHORT
This is the first 16 entries of the MFT (16KB). It is needed to
find where the bitmap file is located on the disk.
__MFTSHORT.LOG
This is the ddrescue logfile for the __mftshort file.
__BITMAPFILE
This is the recovered NTFS bitmap file.
_PARTX__BITMAPFILE.LOG
This is the ddrescue logfile for the NTFS bitmap file. There could
be multiple logfiles, each with its own part# (part0, part1...).
Normally there should only be one logfile, but if for some reason
the NTFS bitmap file is fragmented on the disk, there will be a
separate logfile for every fragment.
NTFSBITMAP_RESCUE_REPORT.LOG
This file contains all the results from ddrescuelog -show-status
for all the ddrescue reads used by ddru_ntfsbitmap, and also for
the domain logfile(s).
The format for running ddru_ntfsbitmap is:
ddru_ntfsbitmap SOURCE_DISK LOGFILE [OPTIONS]
Where:
SOURCE_DISK
The drive or partition that you are trying to recover. This needs
to be the EXACT same source as the ddrescue input file that you
will be using for the recovery.
LOGFILE
The name of the domain logfile that you wish to create to use with
ddrescue.
ddru_ntfsbitmap supports the following options:
'-h'
'--help'
Print an informative help message describing the options and exit.
'-v'
'--version'
Print the version number and exit.
'-D'
'--debug'
Turn on debugging and create a debug file. The name of this file
is 'ntfsbitmap_debug.log'. It is mostly for my use in
troubleshooting bugs. I may ask for this file if someone reports a
problem that I am unable to identify from their description.
'-V'
'--verbose'
Show additional information. Right now all this shows is the
commands sent to ddrescue. This could help if you are trying to
pass options to ddrescue and it is not working correctly.
'-g CLUSTERS'
'--mingap CLUSTERS'
The minimum number of unused NTFS clusters between the used
clusters. The default is 0 (allow all gaps), and the maximum
allowed value is 4096. Any number higher than the maximum will be
lowered to the maximum. The purpose of this option is to bridge
small gaps of unused space, which will make the output domain
logfile smaller, and possibly speed up reads a little bit, although
the speed increase may not be significant (if at all). This will,
however, add some extra reported used space, and cause more data to
be read than needed. How much data will depend on how many gaps
there are of the size chosen. The benefit of using this option
would vary for every situation, and is not yet proven. A typical
NTFS cluster is 8 sectors (but can vary), so with a sector size of
512, a value of 16 would be 64KiB. A value of 256 would be 1MiB. A
value of 4096 would be 16MiB. The idea is to use the lowest number
that may give some benefit.
If you are considering using this option, I would recommend running
it with different output domain logfile names to see how it is
going to affect it. Once ddru_ntfsbitmap has completed the first
time, and you have not deleted any of the output files, you can run
it multiple times afterwards and it will not perform any additional
reads (unless you specify retries in the ddrescue options). For
instance:
ddru_ntfsbitmap /dev/sda1 domain_logfile
ddru_ntfsbitmap /dev/sda1 -g 16 domain_logfile16
ddru_ntfsbitmap /dev/sda1 -g 256 domain_logfile256
ddru_ntfsbitmap /dev/sda1 -g 4096 domain_logfile4096
You can then examine the output files to see the differences, and
most notably see the size difference of the files. You can also
use the 3rd party tool ddrescueview to view the output domain
logfiles to help see a visual difference. Also, PAY ATTENTION to
the used percentage reported at the end of each run. If the used
percentage jumps up too much, then any benefit is completely lost
and you should use a lower value. I would like to restate that any
benefit of using this option is not yet proven, and using a number
too high will have the opposite effect.
'-i BYTES'
'--inputoffset BYTES'
Set input offset (partition offset). This is needed if doing a
whole drive recovery, to specify the offset of the NTFS partition.
You need to specify this offset if you will be using an input such
as "/dev/sda". You can get this offset by doing a little math on
an "fdisk -lu" command (the "u" gives the results in sectors, which
is needed for this to work). Let's look at the following results
from "fdisk -lu /dev/sda", where /dev/sda is the source disk you
wish to recover.
Disk /dev/sda: 5 GB, 5362882560 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10474380 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/sda1 2048 10485759 5245191 7 HPFS/NTFS
Warning: Partition 1 does not end on cylinder boundary.
This tells us that the NTFS partition /dev/sda1 starts at sector
2048. The units tells the sector size, which is 512 bytes. So
multiply the unit size (512) by the start (2048), which gives us
1048576. This number is the offset in bytes, which is what you
supply to this option. So your ddru_ntfsbitmap command would look
something like this:
ddru_ntfsbitmap /dev/sda -i 1048576 domain_logfile
If you do not supply the correct offset, you will get an error
stating the boot sector ID is not NTFS, and the program will exit.
The boot sector file and the corresponding logfile will also be
deleted (files will not be deleted if using the -debug option).
'-o "OPTIONS"'
'--options "OPTIONS"'
Ddrescue options to pass directly to ddrescue. Use quotes around
the whole string of options. For example:
ddru_ntfsbitmap /dev/sda1 domainfile --options "--direct --no-split"
These options will be passed to all calls to ddrescue. Note that
you cannot use the options '--input-position', '--output-position',
or '--size', as these are used by ddru_ntfsbitmap for control. If
you try to pass one of these options, you will likely get an error
message from ddrescue.
'-m FILE'
'--mftdomain FILE'
Creates a separate additional domain file for the MFT (master file
table). This mft_domain_file can be used the same way as the
examples below, just insert mft_domain_file in place of the regular
domain_logfile. The purpose of the mft_domain_file is to allow
recovering of the most important part of the filesystem. You can
use this before using the regular domain_logfile to attempt to
recover the MFT first, and then use the regular domain_logfile to
then recover the rest of the data. You could also use it later on
to just focus on the MFT. It could also be useful to see if the
filesystem has errors, and how many, which could help with your
decision on how to proceed.
To create both a regular domain and also a MFT domain file:
ddru_ntfsbitmap /dev/sda1 domain_logfile -m mft_logfile
Then to focus on the MFT your ddrescue command would be:
ddrescue -m mft_logfile /dev/sda1 recovered_ntfs_image rescue_logfile
'-r'
'--restart'
Delete all output files and start over. The default is for
ddru_ntfsbitmap to resume an attempt where one or more of the
ddrescue reads had errors and you wish to continue trying to get
the most data (possibly using different ddrescue options). However
if you did a wrong option once, or had something left over from a
previous rescue you could get weird results or errors. This allows
you to start over without having to manually delete the previous
files.
EXAMPLES:
PARTITION TO IMAGE-
The simplest example is if recovering only the partition to an image
file.
Let's start with the following fdisk -lu result:
Disk /dev/sda: 5 GB, 5362882560 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10474380 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/sda1 2048 10485759 5245191 7 HPFS/NTFS
Warning: Partition 1 does not end on cylinder boundary.
The ddru_ntfsbitmap command would be something like:
ddru_ntfsbitmap /dev/sda1 domain_logfile
Your ddrescue command would be something like:
ddrescue -m domain_logfile /dev/sda1 recovered_ntfs_image rescue_logfile
WHOLE DISK TO DISK OR IMAGE SIMPLE-
Let's start with the following fdisk -lu result:
Disk /dev/sda: 5 GB, 5362882560 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10474380 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/sda1 2048 10485759 5245191 7 HPFS/NTFS
Warning: Partition 1 does not end on cylinder boundary.
You will need to use the -i (-inputoffset) option, and you will need to
do some math (see the inputoffset option description for more detail).
Multiply the sector size (512) by the partition Start (2048) to get
1048576, which is the input offset for the NTFS partition.
Your ddru_ntfsbitmap command would be something like:
ddru_ntfsbitmap /dev/sda -i 1048576 domain_logfile
Your ddrescue command would be something like this respectively:
ddrescue -f -m domain_logfile /dev/sda /dev/sdb rescue_logfile
Or:
ddrescue -m domain_logfile /dev/sda recovered_disk_image rescue_logfile
If there is more than one NTFS partition on the drive, you would just
repeat the above process for each of them, with the proper input offset
for each. You would use the same rescue_logfile in the ddrescue
command, but you would use a separate domain_logfile for each separate
NTFS partition accordingly.
Important Note: When using the -i (-inputoffset) option, the first
"track" (32256 bytes or 63 * 512 byte sectors) of the disk is
automatically included in the created domain file. This first "track"
contains the MBR, partition table, and possibly more needed boot code.
The reason this is included automatically is so you shouldn't have to
worry about making a rescue copy that won't boot due to missing
important stuff.
WHOLE DISK TO DISK OR IMAGE WITH EXTRA PARTITIONS-
If you are planning on recovering the entire disk structure including
other partitions, it starts to get a bit more tricky. But you may need
to do this with some Windows installations, as there may also be a
smaller active boot partition that contains the boot information for
Windows, and this partition would need to be copied for the OS to boot.
Let's start with the following fdisk -lu result:
Disk /dev/sda: 120 GB, 120031511040 bytes
255 heads, 63 sectors/track, 14593 cylinders, total 234436545 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/sda1 63 20466809 10233373 b FAT32
/dev/sda2 * 20466810 143331929 61424527 7 HPFS/NTFS
/dev/sda3 143331930 225247364 40949685 83 Linux
/dev/sda4 225247365 234436544 4586557 f Extended LBA
/dev/sda5 225247428 234436544 4586557 82 Linux swap
Warning: Partition 5 does not end on cylinder boundary.
The first step is to get the NTFS partition (sda2) offset, multiplying
the Start by the sector size (20466810 * 512 = 10479006720). So then
your ddru_ntfsbitmap command would be something like:
ddru_ntfsbitmap /dev/sda -i 10479006720 domain_logfile
Your ddrescue command would be something like this:
ddrescue -f -m domain_logfile /dev/sda /dev/sdb rescue_logfile
Now you want to also recover the FAT32 and Linux partitions. You need
to do some math again. For the FAT32 partition (sda1) multiply the
start by the sector size (63 * 512 = 32256). This is the input position
you provide ddrescue. Next subtract the start from the end, and then
multiply that by the sector size (20466809 - 63 = 20466746, * 512 =
10478973952). This is the size you provide ddrescue.
So now your next ddrescue command would be something like this:
ddrescue -f -i 32256 -s 10478973952 /dev/sda /dev/sdb rescue_logfile
And we do the same for the Linux partition. Input position = (143331930
* 512) = 73385948160, and size = ( (225247364 - 143331930) * 512) =
41940702208.
Ddrescue command:
ddrescue -f -i 73385948160 -s 41940702208 /dev/sda /dev/sdb rescue_logfile
I am not going to get into the Extended partition, except to say that I
am pretty sure that you must copy the first part of it (starting at sda4
in this case). I have probably covered what the average person will
ever do with this already.
4 ddru_ntfsfindbad
******************
Ddru_ntfsfindbad is a utility for NTFS partitions to find which files
are related to bad sectors in a ddrescue log file. While it only works
for NTFS partitions, it is MUCH faster then the original ddru_findbad.
It also gives more useful output. And it does NOT require any 3rd party
utilities. It will also do the best it can to work with a damaged file
system (and even give you an idea of how damaged). While it may keep
going if physical read errors are encountered, it is designed to work
using the recovered disk or image file, NOT the original failing drive.
While ddru_ntfsfindbad will process a damaged filesystem, it does
require a few things. It needs to know where the ntfs partition starts
(not needed for partition only image, as the location will be 0). It
needs to be able to read the partition boot sector (512 bytes). It
needs to be able to read the first entry of the MFT, or the first entry
of the MFTMIRROR (1024 bytes). If it has that information, then it will
proceed as best it can. If there are no errors in the MFT, the output
results should be accurate. If there are errors in the MFT, you may be
in for a rough recovery as the MFT is very important to recovering
files.
Ddru_ntfsfindbad does not process deleted MFT entries, as its purpose
is not to find deleted files. It will however process entries in the
recycle bin, as they are not truly deleted, although you will clearly
see in the name that they are in the recycle bin.
The output file will tell you if the error was in a file or folder.
If it was a file, then most likely that means actual file damage. If
the error was in a folder, that is a bit different. That means that the
folder is damaged and likely has lost some of the files/folders that
were in it, and by that I mean it lost the link to them, not the files
themselves. That means that when exploring the filesystem they will not
show up. As an example of what this could mean, I have found that the
recovery tool testdisk appears to need the folders to be intact to find
and recover files, while more advanced (and likely not free) tools such
as R-Studio will find them. Ddru_ntfsfindbad acts more like R-Studio,
as it doesn't even look at the data contained in the folders. It builds
the folder paths from the inodes themselves (every inode has the number
of it's parent inode, so a map can be built without needing any extra
data from the folder except the parent inode number listed in the actual
MFT entry). Please note that I am not endorsing or condemning any
particular software here, only making reference to examples that I have
personally observed.
As the output file shows what files have errors, any errors to the
file $MFT means that your filesystem is damaged (this will be at the
very top of the list if it has errors). As the MFT is critical in
recovering the files, there is no guarantee for recovery if it is
damaged. Errors mean missing inode entries, and if the entry was in use
then you are missing something important. If the entry was a file, then
how to find the file on the disk is lost. The only way to recover from
a missing file entry is to scan the whole disk with a recovery utility
such as photorec, and these utilities can be hindered by file
fragmentation and by the fact that there could be error sections in the
files themselves (good luck). If the entry was a small file (about 800
bytes or less), then the file was likely contained within the inode
record itself, and will be lost. If the missing entry was a folder,
then the files and sub folders may still exist, but they will be
orphaned, and will not show up when normally exploring the filesystem,
although they may still be able to be recovered (and the windows
checkdisk utility might be able to fix the links). Errors in the MFT
can mean an uncertain recovery, and you will have to work for it to get
all you can.
The normal output file is:
NTFSFINDBAD.LOG
This is a list of the files/folders that are found to have errors.
Inode= the NTFS inode number of the file/folder. Errors= how many
separate contiguous error sections there are. Errorsize= the total
size of all the combined errors in bytes. Note that while this
number would normally be a multiple of the sector size, if an error
was in the last sector and the file did not fill the whole sector,
only the used portion would be included in the errorsize. FILE or
FOLDER tells if it is a file or a directory. Name= the full path
file/folder name. It should normally start with "./" which
indicates the path makes it to the top level. If it does not start
with "./", then it is considered to be orphaned, meaning that the
path does not make it to the top level directory. Errors in the
MFT can cause this.
The format for running ddru_ntfsfindbad is:
ddru_ntfsbitmap SOURCE LOGFILE [OPTIONS]
Where:
SOURCE
The drive, partition, or image file that you have recovered. This
needs to be the EXACT SAME DESTINATION as the ddrescue output file
that you used for the recovery. If you copied /dev/sda to
/dev/sdb, then use /dev/sdb as the source, DO NOT USE a partition
(/dev/sdb1)! If you do not use the exact same destination, then it
will not match the logfile and your results will be totally
inaccurate. If you only recovered the partition (/dev/sda1) to an
image, then you can simply supply that image file with no partition
offset. If you are supplying a drive or an image created from a
whole drive, then you must supply the correct partition offset (see
-inputoffset for more info).
LOGFILE
The name of the logfile from ddrescue.
ddru_ntfsfindbad supports the following options:
'-h'
'--help'
Print an informative help message describing the options and exit.
'-v'
'--version'
Print the version number and exit.
'-D'
'--debug'
Turn on debugging and create a debug file. The name of this file
is 'ntfsfindbad_debug.log'. It is multi-level, meaning -D is level
1, -DD is level 2 and so on. Please note that anything higher than
level 2 can produce a stupidly large debug file that you probably
won't know what to do with. This file would normally be for my use
in troubleshooting bugs. However, I have made level 1 to provide
some useful output to an advanced end user. Inode= the NTFS inode
number of the file/folder. Part= is the number of the file
fragment, starting with 0. If the file is not fragmented then
there will only be a part0. Offset= is the fragment start offset
in bytes in relation to the start of the partition. Fulloffset= is
the fragment start offset in bytes as seen from the beginning of
the disk (will be the same as offset if only a partition recovery).
Size= is the length of the fragment in bytes. Type= is the data
type for the fragment (we are most interested in type=0x80, as this
means actual file data. If you want to know about the other types,
I suggest you do a search for "ntfs mft entry attribute types").
Errors= how many separate contiguous error sections there are in
the fragment. Errorsize= the total size of all the combined errors
in bytes for the fragment. There is no file name in this output,
as that would be listed in the main output file, you can reference
that inode number. Any inodes that were not able to be processed
(hard errors) will also be listed here with a warning message.
Fulloffset= and size= are what you would use to compare the
fragment location to the rescue logfile, so that you could
customize a ddrescue command to make further attempts at recovering
specific data.
'-V'
'--verbose'
Show additional information. It is multi-level, meaning -V is
level 1, -VV is level 2 and so on. At this time I am only going to
provide some info for level 1, as higher levels are more for my
personal use, and anything above level 2 will probably not be
useful to you. Most of the level 1 verbose info is self
explanatory, except for "MFT hard errors". This is the number of
MFT entries that are corrupt in some way, and were not able to be
processed (likely due to bad sectors, but could be for other
reasons beyond my control or knowledge). This could give an idea
of how damaged the filesystem is. If you use level 2, then you
will see a soft error count (they will also show as warnings in
level 2 of debug). All I can say about soft errors is that it
means the inode entry passed the normal sanity checks for
corruption, but then something stupid happened while processing.
This could be something wrong with the entry, or my lack of
knowledge on how to process it (ask Bill Gates).
'-e TYPE'
'--encoding TYPE'
Set the character encoding type for the file name output. The
default is UTF-8 which should be good for most if not all
circumstances. This allows the user to change the character
encoding for the file names, as they are in the format of UTF-16 in
NTFS and need to be converted to something more text friendly. It
uses iconv. To find what types are supported, please visit
"http://www.gnu.org/software/libiconv/", or do a search for "iconv
encoding types". If the conversion has characters that are unable
to convert to the type selected, then a message will be shown on
the screen for every inode stating how many characters were
skipped. There are a couple options that can be added to the
encoding type, "//IGNORE" and "//TRANSLIT". IGNORE means it will
ignore all unconvertible characters by skipping them in the output.
This basically is the same as the default except it will not
produce any messages when unconvertible characters are encountered.
TRANSLIT means iconv will try to convert the unconvertible
characters into the closest thing it knows how, or a default
character (likely the "?" character). It will show on the screen
how many characters were converted for every inode. For example,
to convert to ASCII with attempted translation, you would use the
option:
--encoding ASCII//TRANSLIT
'-n'
'--noconvert'
Turns off the iconv file name conversion and uses the old method of
using every other character. This option has been added in case of
odd program crashes due to iconv being buggy with a memory leak.
This old method will only work proper with normal printable ASCII
characters.
'-i BYTES'
'--inputoffset BYTES'
Set input offset (partition offset). This is needed if you did a
whole drive recovery, to specify the offset of the NTFS partition.
You need to specify this offset if you used an input such as
"/dev/sda". You can get this offset by doing a little math on an
"fdisk -lu" command (the "u" gives the results in sectors, which is
needed for this to work). Note that you can use this fdisk command
on an image file, all you have to do is replace the "/dev/sdb" in
this example with the name of the image file. Let's look at the
following results from "fdisk -lu /dev/sdb", where /dev/sdb is the
destination disk or image you recovered.
root# fdisk -lu /dev/sdb
Disk /dev/sdb: 5 GB, 5362882560 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10474380 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 2048 10485759 5245191 7 HPFS/NTFS
Warning: Partition 1 does not end on cylinder boundary.
This tells us that the NTFS partition /dev/sdb1 starts at sector
2048. The units tells the sector size, which is 512 bytes. So
multiply the unit size (512) by the start (2048), which gives us
1048576. This number is the offset in bytes, which is what you
supply to this option. So your ddru_ntfsfindbad command would look
something like this:
ddru_ntfsfindbad /dev/sdb logfile -i 1048576
Let's look at an example from an image file:
root# fdisk -lu alice.dd
Disk /media/data/alice.dd: 160 GB, 160039272960 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312576705 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/media/data/alice.dd1 2048 20482047 10241406 27 (null)
Warning: Partition 1 does not end on cylinder boundary.
/media/data/alice.dd2 * 20482048 312578047 146054947 7 HPFS/NTFS
Warning: Partition 2 does not end on cylinder boundary.
This tells us that the NTFS partition alice.dd2 starts at sector
20482048. The units tells the sector size, which is 512 bytes. So
multiply the unit size (512) by the start (20482048), which gives
us 10486808576. This number is the offset in bytes, which is what
you supply to this option. So your ddru_ntfsfindbad command would
look something like this:
ddru_ntfsfindbad alice.dd logfile -i 10486808576
If you do not supply the correct offset, you will get an error
stating the boot sector ID is not NTFS, and the program will exit.
EXAMPLES:
PARTITION ONLY TO IMAGE RESCUE - If your ddrescue command was:
ddrescue /dev/sda1 rescued_image rescued_logfile
Then the ddru_ntfsfindbad command would be:
ddru_ntfsfindbad rescued_image rescued_logfile
WHOLE DISK TO DISK RESCUE - If your ddrescue command was:
ddrescue /dev/sda /dev/sdb rescued_logfile
Then you would have to use the -inputoffset option (see the option
details above for how to get the offset), so the ddru_ntfsfindbad
command would be something like:
ddru_ntfsfindbad /dev/sdb rescued_logfile --inputoffset 1048576
WHOLE DISK TO IMAGE RESCUE - If your ddrescue command was:
ddrescue /dev/sda rescued_image rescued_logfile
Then you would have to use the -inputoffset option (see the option
details above for how to get the offset), so the ddru_ntfsfindbad
command would be something like:
ddru_ntfsfindbad rescued_image rescued_logfile --inputoffset 1048576
5 ddru_diskutility
******************
Ddru_diskutility is an advanced LINUX ONLY utility that can perform
several different functions on a disk, using some direct pass-through
disk commands. It can read sectors to the screen (reading to a file is
not supported yet). It can read using 4 different methods: normal,
direct, scsi-passthrough, and ata-passthrough. It can perform a device
inquiry to get things such as model and serial number. If supported, it
can perform readlong commands, both 28 bit and extended, with the option
to get the best average of a set of reads.
Ddru_diskutility is for advanced users, so I am not going into great
detail in this documentation. If you don't understand what it does,
then don't use it!
The format for running ddru_diskutility is:
ddru_diskutility SOURCE_DISK [OPTIONS]
Where:
SOURCE_DISK
The drive that you wish to work with. This NEEDS to be a reference
to the WHOLE DISK, and NOT a partition. All of the direct
passthrough commands will react as if the whole disk was selected,
so it is very important to use reference the whole disk so you get
accurate results!
ddru_diskutility supports the following options:
'-h'
'--help'
Print an informative help message describing the options and exit.
'-v'
'--version'
Print the version number and exit.