external hard disk help needed

[gregbradley]

I was using an external hard disk for storing some astro data.

I plugged it into my Vista computer to read some files. It never got there.

Now when I plug it back into my Win 7 laptop I get the drive detected but I can't access files. I get corrupted file or directory error message.

Any suggestion on what to do?

It also asks to format the drive.

On my observatory computer one of the hard disks did something similar about 4 months ago. If I click on that hard disk I get an error saying the disk is not formatted and asks if I want to format it now? (I don't).

Hard disks seem very flimsy and unreliable these days. They have massive capacity but seem to fail very easily.

Any suggestions?

Greg.

[Ric]

Hi Greg

I'm having the same problem with my external HD as well.

It's a Western Digital 1Tb, It's also telling me to format. There was no warning, I just plugged it in and it was a no go.

I'll also be grateful for any suggestions from other IIS members.

Cheers

[supernova1965 (Warren)]

Either run a Live Linux CD or go to a friend who runs Linux natively and it should if the HDD isn't dead completely which it doesn't sound like it is to me and you should be able to recover data and then let windows format the HDD. Hope this helps.

[Barrykgerdes]

Sounds a bit like a write sequence has been interupted either by a power failure, bad connection (USB cable) or accidental removal. In which case the error inhibits the Partition table,Directory or FAT table from being accessed.

There are repair programs that can fix this kind of fault without data loss. ScanDisk may even fix it. The ease of examining the disk will depend on your operating system. The current O/S's are not DOS based and the repair programs need to load a version of DOS so that the HDD can be addressed natively.

The MBR may also be corrupt. These programs can also write a generic MBR.

Barry

[Colin_Fraser]

Originally Posted by gregbradley

I was using an external hard disk for storing some astro data.

I plugged it into my Vista computer to read some files. It never got there.

Now when I plug it back into my Win 7 laptop I get the drive detected but I can't access files. I get corrupted file or directory error message.

Any suggestion on what to do?

It also asks to format the drive.

On my observatory computer one of the hard disks did something similar about 4 months ago. If I click on that hard disk I get an error saying the disk is not formatted and asks if I want to format it now? (I don't).

Hard disks seem very flimsy and unreliable these days. They have massive capacity but seem to fail very easily.

Any suggestions?

Greg.

Try this Greg.
In the file manager...
1) right click the drive in the directory tree...
2) Select Properties..
3) Select Tools
4) Click the Check Drive button
5) Check the box Automatically fix file system errors
and if you want also check Scan and Recover bad sectors
6) Click Start button

This usually fixes enough errors to be able to at least recover files.

Hope it helps.

[bojan]

I had similar problem (after HD hit the floor while being switched ON), and I managed to fix it by using another OS - Linux.
Where W' wouldn't show anything at all (or errors) Linux would read it like there were no problems at all.
So I simply transferred all "corrupted" files to other HD, and all my problems were solved.

[John0z (John)]

Greg,

What size is the external hard disk? Why I ask, is that usually the first thing we do for data recovery is to make an image of the disk. This is generally done via Linux - to make a block copy of the disk to an image file.

Is the data on the disk very critical or important? I.e. do you have any copy of it, hence the need to recover the files.

If you are anywhere near Dundas, I can help you to recover your data. The process that I would use is as follows:

1. Connect the external disk to a workstation with a large disk.
2. Boot from Linux and make a copy of the external disk - i.e. using dd
3. Once the copy is done, we can try to use Linux to access the disk - usually as people have already indicated, Linux is quite tolerant of errors that Windows just throws up its hands on.
4. If accessible, the data can be copied onto the workstation disk.

Once we know we have a backup of the disk, we can then look at why the disk is not accessible from Windows - or we can work on the disk image to recover data - this is where Linux is good, because the disk image can also be mounted as a read-only file system.

I would also run diagnostics on the disk - usually available from the manufacturer. I have had a fair bit of experience in recovering data from disks, even from servers remotely in Belgium and in China.

If you have a spare machine to try this on, I can give you some idea of how to use a Linux such as Knoppix to get started.

-John

[Poita (Peter)]

John gives good advice do *not* attempt to run chkdsk or any other tools on the drive if the data is critical, a backup needs to be attempted first using a block copy program like dd or similar.

Also, it could be the electronics in the external casing, you can remove the drive from the case, and just plug it straight into the sata connectors inside your PC if you have a desktop and see if it comes up.

I pay a little more for the enterprise HDDs these days instead of the consumer models. They cost a little more but seem to be far more reliable.

-Peter

[gary]

Originally Posted by John0z

1. Connect the external disk to a workstation with a large disk.
2. Boot from Linux and make a copy of the external disk - i.e. using dd

Hi John,

What I would commend to you as part of your portfolio of disk recovery techniques
under Linux is rather than do a straight dd is to use GNU ddrescue.

When you perform a straight dd, even if the noerror flag is set, when it hits a bad
sector, it will fill the block with nulls.

Ddrescue does not write zeros to the output when it finds bad sectors in the input, and
does not truncate the output file if not asked to. So, every time you run it on the same
output file, it tries to fill in the gaps without wiping out the data already rescued.

It is very powerful when used with its log file facility and employs an
algorithm which includes the ability to try reading sectors backwards and to
perform multiple retries.

When used with a log file, it can be interrupted at any time and then started
again without loosing the image you have recovered thus far.

Anecdotally, I have used it to recover data from TB sized disks which dd
alone would not have recovered. For example, I have on occasion started with
a disk where megabytes would have been lost with just using a straight dd but
using ddrescue have created a new image where only 16 kilobytes of data was lost
out of the 1 TB. As it is operating, it is most gratifying to watch the error count
drop and drop.

GNU ddrescue web page here -
http://www.gnu.org/software/ddrescue/ddrescue.html

GNU ddrescue man page here -
http://www.gnu.org/software/ddrescue...ue_manual.html

ddrescue appears on most of the standard Linux recovery distributions these days.

[gregbradley]

Thanks for the replies.

John I think its about a 250gb hard disk or perhaps 500gb.

Windows says the drive is not accessible so scandisk or error check doesn't go past that error message.

So I'll try the GNU Rescue and if no go I may take you up on your offer John.

Thanks for all the informative replies. I knew there would be lots of good advice on this site for this issue.

Greg.

[Ric]

My thanks as well to everyone.

Lots of great info here to work with.

Cheers