14 replies to this topic

[maanu]

ok here is the situation . (i am assuming)

1. i have a bad hdd with lots of bad sectors .

2. i want to image it first (whole hdd) to a safe location so that my data is safe ,before i start some recovery tools on that hdd.

3. so i go ahead and start to make an image of WHOLE hdd with lets say GHOST , or any other tool .

but it does not even START , due to bad sectors on the hdd . or lets support it starts but ends after a while , and does not make full image.

4. now , i could not find any tool which can do the following ,

SKIP the bad sectors and just copy the GOOD sectors off the HDD to the image file .

technically it will be the clonedisk's first option , Image to DISK , with RAW.

but there is not that option i am talking about , that it can ACTUALLY SKIP THE BAD SECTORS and just copy the GOOD sectors as RAW image .which i can later mount with imdisk (and i suppose it will have all my partitions too ? ) and copy the files i need.


diskgenius does not even have the HDD CLONE option. the only tool i can think off right now is clonedisk .

[erwan.l]

ok here is the situation . (i am assuming)

1. i have a bad hdd with lots of bad sectors .

2. i want to image it first (whole hdd) to a safe location so that my data is safe ,before i start some recovery tools on that hdd.

3. so i go ahead and start to make an image of WHOLE hdd with lets say GHOST , or any other tool .

but it does not even START , due to bad sectors on the hdd . or lets support it starts but ends after a while , and does not make full image.

4. now , i could not find any tool which can do the following ,

SKIP the bad sectors and just copy the GOOD sectors off the HDD to the image file .

technically it will be the clonedisk's first option , Image to DISK , with RAW.

but there is not that option i am talking about , that it can ACTUALLY SKIP THE BAD SECTORS and just copy the GOOD sectors as RAW image .which i can later mount with imdisk (and i suppose it will have all my partitions too ? ) and copy the files i need.


diskgenius does not even have the HDD CLONE option. the only tool i can think off right now is clonedisk .

Hi Maanu,
Clonedisk will automatically offer you to skip bad sectors when you hit the clone button.
For every bad block (64k), it will instead write 0's into the destination image file.
If there are actual bad blocks, clonedisk will notify you offering to not ask you the question next time.

Regards,
Erwan.

[Wonko the Sane]

Maybe you looked in the wrong place.

Let me introduce to you DrDD :
http://www.boot-land...?showtopic=7783

Do understand that depending on the type of HD error when a BAD sector is encountered, different things can happen, so your mileage may vary, but you can use the forward/backward capability of DrDD to get the most of the drive correctly and then re-assemble the "holes" with blank sectors.



Wonko

[maanu]

thank you both of you for the kind replies .

@ Wonko the sane

i know about Dr.DD , from long time ago when you mentioned it first time.
i have yet to get a hdd to experiment it with . thank you for reminding me about it .

by the way , diskgenius does have the clone option with VALID sectors only ,
but it is disk to disk

http://www.dgisok.co...l/clonedisk.asp

[Wonko the Sane]

@maanu
You are apparently missing a point.

A number (read MOST if not ALL) disk copying/cloning utilities will throw an error when accessing a "problematic" hard disk bad sector/area, this can create ANY of the following:

• a gargantuan amount of (needless and unuseful) retries which will dilate the time needed to make the image to an incredible number of hours
  
• a system lock (with huge delays as #1 above, only worse, as the procedure needs to be attended to reset the system)
  
• a HD lock (with huge delays as #1 above, only worse, as the procedure needs to be attended to reset the system)

In any case an unwanted additional amount of stress is going to be induced to the (failing) HD.

The general idea is:

• get the MOST data you can in AS LITTLE time and number of attempts possible, a failing HD can die at ANY moment, and what you have not ALREADY got may be lost forever
  
• once you have the most data, try again "narrowing" the "gaps" with a new attempt to recover more data around the bad area

BTW, whilst I do know your "obsession" with diskgenius, the link you provided is saying that it uses an approach like:

FIRST:

• clone MBR+hidden sectors
  THEN:
  
• clone a partition, one partition at a time
  OR:
  
• copy only occupied sectors in the partition, one partition at a time
  OR:
  
• copy only files in the partition, one partition at a time

Obviously this ASSUMES that the drive has a MBR with a valid and readable Partition table and for the last two modes, also that partitions have valid filesystems.
This has NOTHING to do with "data recovery", you can use any cloning program, including dsfo for the first mode, and for the last two "modes" you can use any other imaging program that works similarly, like DriveimageXML (adding the MBR copy bit) or XXCLONE, Robocopy, or strarc if you want to do the file based approach.



Wonko

[erwan.l]

Hi Maanu,

I do aggree with Wonko : be careful with you disk as you may not have lots of opportunities to access your datas and back it up.

However, because I am a selfish developper, I am very interested in your feedback
Indeed, I did not have bad hard disks so I could try the "bad sectors" feature only on crashed floppies.

Once you have backuped your datas or once you are done with your disk, please give clonedisk a try on this disk and let me know

Regards,
Erwan.

[maanu]

@ Wonko the sane

yes you got it . but thing is , what utility (easy gui then Dr.DD plz) or easy command line tool , that you recommend to make a FIRST , FAST copy of the failing hdd as you explained .

i got the idea now i guess, dont stress the failing hdd and LEECH (make image?) of the possible data with hurry and with speed. ?


and as you were explaining about diskgenius , it means it is not good to make image of the FAILING hdd since it will assume everything is fine ?

does it really matter if i ask diskgenius to make a EVERY SECTOR copy (is it call the RAW copy as in clonedisk? ) , and it does it assuming it has the valid MBR , valid partition table etc , ?


@ ervan

i am sorry , but i mentioned in one post , i am assuming . i dont have any bad hdd atm either so i cant test it . i am just preparing for the future . or in other words try to gain some knowledge ,.

[cdob]

i got the idea now i guess, dont stress the failing hdd

Yes, this is the main idea.
First decide: are there any importand files to recover?

No: just thrash the broken hard disk.

Yes: imagine there is ONE possiblity to read the files.
Purchase a second hard disk, boot Knoppix and launch dd_rescue.
http://www.forensics.../wiki/Dd_rescue
http://paulski.com/zpages.php?id=1913
Clone the hard disk. Rescue data at copy hard disk.

[Wonko the Sane]

maanu

You still seem to miss some subtleties.
The "objects" involved are (using the NT terminology):

• \\.\Physicaldrive
  
• \\.\LogicalDrive <-drive letter
  
• File

A physicaldrive is the actual hard disk, and is mapped in sectors, starting from first sector on the disk up to last sector on the disk.
A logicaldrive is an actual partition, and is mapped in sectors, starting from whatever is the start sector in partition table, up to whatrever is the last sector in partition table.
A file is a filesystem object, and is mapped in sectors or clusters of sectors according to the filesystem tables, and can be non-contiguous.

Imagine that you have to read your name in this string:
01m234a5678an9uAB
0 is the beginning of the physical drive
B is the end of the physical drive
1 is the beginning of the logical drive
A is the end of the logical drive
m is the beginning of the file
u is the end of the file
2, 3, 4, 5, 6, 7, 8, 9 are unused sectors (yes, you have a fragmented name )

If everything is OK, you access the physicaldrive, and you know that anything from 0 to B may contain your name.
If everything is OK, you access the logical drive, and you know that everything from 1 to A may contain your name.
If everything is OK, you access the filesystem, and from its tables you know that you have to get characters #3,5,7,8,9 to get "maanu".



Now try doing the same starting from this:
0xm234a5678an9uyB

If everything is OK, you access the physicaldrive, and you know that anything from 0 to B may contain your name.
Since you have not anymore 1 nor A you DO NOT know where your name may be, and you have no logiacal drive to access.


Now try doing the same starting from this:
0xm234a5###an9uyB
where:
# is a BAD AREA that will take you three hours of attempts before crashing your "normal" cloning program.

A dd_rescue or Drdd, or similar programs made explicitly for the imaging of "bad" media have features to help minimize the attempts and save the most data available, in this example result would be:
0xm234a5___an9uyB

A similar program to dd_rescue, but GUI and for Windows, is RAW copy:
http://www.roadkil.n...hp/P22/Raw Copy

On the page cdob linked to there are other Linux utilities, with slightly different capabilities/features, badsically this kind of programs won't error out when finding a bad sector, they will only try a few times, then they will write a blank sector and go on.

Since everytime that a bad sector is found the program slows down very noticeably (doing other attempts), and knowing that very often bad areas (typically those due to a head crash) are a contiguous set of sectors, with Drdd strategy you can try to speed up the things, in the case of a single BAD area:
Read from the beginning.
Find first BAD sector in the BAD area.
Start imaging from the end.
Find last BAD sector in the BAD area.
Join together the two pieces, filling the gap with blank sectors.


Wonko

[ksanderash]

Wonko, thanks again and again, an entire ocean of information and explanations from you!

A nice approach towards a bad sectored HDD has commercial HDClone app.

It has a free version that can be used by a home user to copy a whole HDD to an image (or to a brand-new HDD). The reading speed of deeply faulty drive is kinda surprizing -- ones can think that HDClone don't even see the defects, so fast it works. But after copying the alive sectors the program gets nag with bad ones! And this process can last for days and weeks (till the drive will not die completely, I suppose).

I had two cripple drives that were ought to be data recovered, and the only app (on that time) that I could suggest was Symantec Ghost. Well, it got stuck on reading disk structure for an hour at least, and I stopped the process. Then my eye fall on HDClone (after Acronis surrendered too), and to my amazement it did her best and completed the task successfully.

Thus I can recommend this appy to everyone with such troubles.

...

And as soon as I get my hands on another limped hdd, sure I'll give a try to Clonedisk by erwan. Nice appy, but how it does with bad media, let's see

[Wonko the Sane]

Wonko, thanks again and again, an entire ocean of information and explanations from you!

Only too happy to be of use.

Your report of HDDClone working allright for you is interesting.

BUT as a general rule. when doing data recovery you should use (as opposed to "normal applications") "data recovery" or "forensics" oriented applications, they may be slower, but they give a bigger probability of getting more DATA (the ONLY thing of value).

Often you have no evidence that "program a" is better/faster/more accurate than "program b" unless "program a" fails and you try "program b" and it works, more often than you may think, letting a defective hard disk cool down allows for reading sectors otherwise unreadable, doing partial images is very often the only possibility.

As well you could be surprised by the differences you can find on really problematic hard disks between imaging "forward" and "backwards".

We have a saying in Italy:
[Italian]

La gatta frettolosa fece i gattini ciechi.

[/Italian]

That translates roughly to:

The hurried she-cat made blind kittens.

When doing data recovery patience should be your main attitude.


Wonko

[ksanderash]

Yes, I accept all of what you've sad, Wonko, but I needed to get the data in a hurry, not hours or days The DataRecovery software can have a switch for number of attempts to reread the group of faulty sectors, but it doesn't realy help -- driving into bad zone the drive retreat into himself completely, and the software can receive the response on its actions only after a 10 seconds or so. There are not a thousand of sectors, but more, and the process stretches out impermissible long.

Maybe I'm too fidget person, but can't bear that grinding sound of jerking heads It unhappy reminds me about my first own hdd -- IBM DTLA (RIP).

[steve6375]

WtS's algorithm for try from sector 0 to end - when hit error try from end to beginning, then try to get the bad bits in the middle is THE only sensible way to get data from a damaged hard (fast spinny thing) disk.

The reason for this is that most bad hard disks have had a head crash. This means that there are large lumps of magnetic 'boulders' and ploughed troughs in the head crash region. Now if you use an ordinary clone tool - it will hit this bad area and keep hitting it (recalibrate - hit- recalibrate - hit) until the disk drive heads are completely smashed to bits (7200 rpm boulders hitting disk drive head hovering 10nm above the surface again and again and again and ...).

This is why 'bad hard disks tend to go quickly' - it is because you keep smashing the delicate head into boulders and swarf lying on the disk! So when trying to recover data from a disk you must avoid the bad areas at all costs. Hence use a properly designed program!

[ksanderash]

I believe the drive with heads hanging down on the surface must be disassembled (for mechanism interchange), not readed

And yes, if we are talking about commercial data recovery (as a business thing), then will be different patterns of reading, algorithms, technics, whole hard'n'soft-complexes, etc. But an ordinary home user (maybe even from BootLand) wants only one button to be pressed -- "make my problem gone"

[Wonko the Sane]

-- "make my problem gone"

...or "make it much worse than it was because I was in a hurry"

Doing things in a hurry IS foolish.
Using "inadequate" tools IS foolish.

You can do it allright , but now you know.
Check the "But ... then, why?" in my sig....


Wonko