AVC760 data retrieval

I have a very big problem with an AVTECH DVR, model AVC760.

I have installed the above DVR in one of my customers. This was the

myfirst DVR installation.

Two days ago my customer had an incident and it was recorded in the DVR.

Because i didn't know how to take backup from the DVR, i removed the

hard disk from the DVR and i tried to put it in my desktop computer (WINDOWS) as a slave to access the files.

Disk does not appear in "My Computer" , but i can see the disk in "Device Manager" and "Disk Management" although is recognized as an "Unallocated Disk".

I realised that the disk was unreadable, unallocated because of a different file system so i put it back again in the DVR.

That was it. The DVR was saying "NO DATA" when i was trying to search

for the files and the available capacity of the disk displayed, was like there was no data.

I have tried also to read the disk from LINUX and MAC OS with no luck.

Does anyone, from experience, know a way to get the data from the hard disk?

Although I am not an AVTech expert, I am pretty sure I know what happened.

Windows will write a disk signature when it detects a new disk. The 4-byte signature is located at offset 0x1b8 from the start of the Master Boot Record (physical sector 0).

AVTech, and others (ICRealtime Pro for instance) do not partition the disk the way a standard operating system would. They seem to write to the raw disk. If one were to use a disk sector editor and put those bytes back where they were, then the disk should be usable again. That value should be all zero's, but could be verified by checking a good DVR disk.

The bad news is that it sounds like the DVR went ahead and setup the disk again when you put it back in. In that case all the indexes would have been wiped clear. It would take someone with detailed knowledge of the AVTech file structure to recover it then.

Dave

Dave,

thank you very much for your advise.

Few hours ago i visited again the customer and place the hard disk back to the DVR to try getting data out using the software (via ethernet) came with AVTECH but again with no result. "NO LIST DATA"

So it's what your are saying that happened.

Is there a software that can bring the hard disk to a previous condition?

Where can i find a disk sector editor?

Unfortunately, i've sent many e-mails to AVTECH about my problem and i've got no answer.

Without the technical knowledge of how the DVR stores the data, or help from the manufacturer, you are probably out of luck. The utilities for Windows recovery are designed for a standard file system that is used on millions of computers. If you knew about the damage before re-installing the disk you might have been able to fix those sectors up, but it looks like the disk was cleared by the DVR.

A data recovery company might be able to help, but they are very expensive. If you are really good with computers (expert) and have a lot of time on your hands you could give it a shot.

Before you do anything with the disk, I would clone it using something like Ghost.

I guess I'm saying with enough money and time almost anything can be done, but is it worth it?

You can go to http://en.wikipedia.org/wiki/Disk_editor to find out about disk editor software.

Dave

I had almost the same problem like Kgero. Just like DaveM said that the hard disk is in raw mode. But using data recovery software I manage to get back the data files (gz and swf files). I try to play the swf files but it just freezed (the smallest is about 200MB). How can I play the big swf files? I also try to extract the gz files with winrar but it seems to be corrupted.

pyjo i 've done the same thing. i tried to get some data using a recovery software. I have many .gz files, one of them is 12GB, but when i try to open them with WinRAR, it says that files are corrupted.

I have not given up yet. if you come to a solution please let me know.

kgero, so far I have no luck with converting the swf file with winavi. I probably think that the swf is as corrupted as the gz files. Anyone has a working solution?

I had almost the same problem like Kgero. Just like DaveM said that the hard disk is in raw mode. But using data recovery software I manage to get back the data files (gz and swf files). I try to play the swf files but it just freezed (the smallest is about 200MB). How can I play the big swf files? I also try to extract the gz files with winrar but it seems to be corrupted.

i had same problem with u bro,

what recovery software you use ?

pls let me know

because im using stellar phoniex and ufs explorer

i found so may .data files

best regard