Data recovery and reformatting

[coxsone]

Hi all-
Hope someone can help out. I have an external USB drive that was split into two partitions. All the data on one of the partitions doesn't mount or show any data. The other partition does. Not sure why one partition seems to be fine. I imagine that something is corrupted on that partition.

I want to try to recover the data but when I run a data recovery program, the entire drive ejects itself before the scan is completed.

So - my main question: let's say I reformat the bad partition. Is there a chance that a data recovery program would be able to access some of the files on that partition? Any other ideas of what I can do for a bad partition?

(I only backed this data up to one place only to find out that drive has failed. So...bad luck and now I'll have to be sure to back up in more than one place. This isn't super crucial information but it's stuff I'd like to rescue.)

 

[organicCPU]

let's say I reformat the bad partition. Is there a chance that a data recovery program would be able to access some of the files on that partition?

There is and there are people around that swear on this method, but I would never ever recommend it. -> Don't reformat.

Any other ideas of what I can do for a bad partition? ...but it's stuff I'd like to rescue

If you really want this stuff back, take it to some professional data recovery service and stop using the drive immediately.

If you can live without this stuff and say you try by yourself, that's a different thing.
My post in this thread is more or less identical to what I would tell you here, except that the OP there tried to recover an internal drive and not an external USB drive and that the B-Tree was erased and not corrupted, like yours ATM could be. The steps for you to do are almost the same.

As USB is not the ideal interface for recovery, it probably has better chances to attach the drive via Thunderbolt or eSATA.
After making sure you're prepared, start backing up the working partition if you like that stuff, too.
Then try to make a block level copy of your failing partition.
If you then do have a 1:1 disk image clone of your failing partition, you can start trying to fix the actual drive or scraping data out of your clone.
That means much patience, an additional working drive that is large enough to hold your external USB failing partition size at least twice and of course a good portion of luck!

 

[Fishrrman]

"I have an external USB drive that was split into two partitions. All the data on one of the partitions doesn't mount or show any data. The other partition does. Not sure why one partition seems to be fine. I imagine that something is corrupted on that partition."

I had a problem EXACTLY like this one several years' back.

I had a drive that was partitioned. One partition was used to store mp3 files.
One day, I connected the drive, and the mp3 partition .... wasn't there. The other partitions were fine, but the one I WANTED to access was... gone. Nothing would bring it back.

Eventually, I tried something that seemed "the wrong way to do it".
BUT... SURPRISE!... I got the files back.

So... here's my advice on what you should do if nothing else works.

First, before you try my advice, I suggest you try more than one "data rescue" app.
The premier one for the Mac is "DataRescue" by ProSoft.
But there are others as well.
If they get you nowhere, then the next thing to do is try "my advice".

When I first tried to run DataRescue on the drive, I got nowhere because the corrupted partition wouldn't mount and DR didn't "see it".

Here's what I did:
I RE-INITIALIZED the ENTIRE drive into ONE partition.
Yes, you read that right.
I erased it.

HOWEVER -- AND THIS IS VERY IMPORTANT -- I DID NOT "zero out" the drive (that is, I did not do a "secure erase").
Instead, I just did a quick re-initialization. This replaces the old (corrupted) directory with a fresh (empty) one. BUT IT LEAVES ALL THE DATA OUT ON THE PLATTERS UNTOUCHED. (all shouting is intentional)

Now, the drive would mount on the desktop, but look "empty" -- no files on it.
But the reality is, all the old files ARE STILL THERE, out in the sectors of the platters.
The drive looks "empty" because [only] the directory has been replaced.

Now, I ran DataRescue again.
This time, it found the mounted drive on the desktop.
I could get it to scan the drive, looking for the lost mp3's.
And... it found them!
DR was able to do this because it "ignored" the empty directory, and instead went "right to the platters", where it was able to find the data. It then scavenged what it found, and re-assembled the data on a "scratch drive" (this is why you need a SECOND DRIVE to which to receive the recovered files).

When DR was finished, I had the recovered files.
WARNING: Many of the file names were lost, and all previous folder hierarchies were lost. This is because file names and folder hierarchies are "constructs" of the old directory, which now no longer exists.
BUT... the DATA still existed, and that's why DR was able to find and recover it.

Because the files were mp3's, they also contained metadata.
So, I found that I was able to just "dump" the recovered files into a new iTunes library, and iTunes then scanned all the metadata, sorted the files, and presented the majority of them to me "as artists, albums, etc.".
After that, I was able to re-create file names and folder hiearchies.
It did take me a few years' (of very random work, a little now and then), to get it all back "in order".
But in the end, I was able to re-construct about 95% of the "lost files".

That was the price I paid for not having backed up those files.
They ARE properly backed up now, in more than one place.

As I mentioned above, this was "not the obvious method" to recover files from a "dark partition". But it worked for me.
If you try several things that don't work for you, you might consider trying my method above...

 

[coxsone]

Thanks so much for your advice! The partition is mounting again all of a sudden. The files are still not visible but I will try with Datarescue DD first and see how that goes.

 

[organicCPU]

You are on the right track making a block level copy. However, some folks reported that they managed to use ddrescue or its graphical user interface wrapper app DDRescue-GUI successfully where Datarescue DD failed.

 

[ZapNZs]

Is this a HFS+ partition?
Out of curiosity, did you check the drive with a SMART app just to see if the drive may be physically failing? (or if it may even be the enclosure?)
If this is HFS+, and after completing the block level copy, do you by chance have access to a copy of DiskWarrior?

 

[coxsone]

Is this a HFS+ partition?
Out of curiosity, did you check the drive with a SMART app just to see if the drive may be physically failing? (or if it may even be the enclosure?)
If this is HFS+, and after completing the block level copy, do you by chance have access to a copy of DiskWarrior?

It is HFS+. I checked with with SMART Utility and Disk Utility. Both could not access the partition. I don't have DiskWarrior.

I haven't taken it out of the enclosure. Think that might help if I connect it with a USB to SATA/IDE cable?

 

[ZapNZs]

It is HFS+. I checked with with SMART Utility and Disk Utility. Both could not access the partition. I don't have DiskWarrior.

I haven't taken it out of the enclosure. Think that might help if I connect it with a USB to SATA/IDE cable?

Are any errors showing in the Console relating to the drive/attempts to mount the volume?

If you have decided you are not seeking data recovery beyond the DIY (and of course have backed up the second volume in the event that the drive is physically failing), IMO trying a different enclosure/connection is always a good place to start in the event of some weird enclosure-induced issue, as unlikely as it may be in this instance.

Someone smarter than me could confirm this, but, hypothetically, even if a single partition on a drive is malfunctioning due to corruption, a SMART app should still hypothetically be able to pull metrics from the physical drive??? - at least, I have observed this with SmartMonTools.

If it were me, the files were important-but-not-essential, and I was able to rule out physical failure (and possibly even if I couldn't), the next thing I would personally do is hit it with DiskWarrior to see if it can mount, diagnose, and (if the diagnostic tool indicates issues) rebuild (and, if need be, scavenge) the directory. An Apple repair shop in your area may have a copy they will loan to you.

 

[organicCPU]

Think that might help if I connect it with a USB to SATA/IDE cable?

Bridging one transfer protocol to another works just as good as implemented by the manufacturer. Means, your actual USB enclosure, if not damaged, could work better as some cable or vice versa. On smartmontools they do have a compatibility chart for USB devices. Keep in mind, that macOS is not able to show S.M.A.R.T. status for external drives out of the box.
Some other users at MR explained, that it's better to use eSATA or Thunderbolt connection to attach defective drives, because of automatic USB error correction. AFAIK, there is a CRC-5 and CRC-16 in USB and a CRC-32 in SATA. I don't know if those cyclic redundancy checks or just a better protocol bridging is the main reason to prefer eSATA or TB over USB to investigate critical disk drives, but I believe that at least cheap consumer USB connectors are more often failing than higher quality eSATA or TB adapters.

 

[Fishrrman]

OP:

Could you tell us a bit more about what KIND of files you will be trying to recover?

 

[coxsone]

hey all - sorry for the delay in response. I had to put this to the side for a while.

Fishrrman: I'm trying to recover music files--MP3, AAC. I had a lot of the stuff backed up but there are still some items I would like to recover.

I did not have success with some of the other suggested applications--the drive under question was either not accessible/visible. Or the app would start working on it and then lose access to the drive.

One important new piece of knowledge I've gained from this experience is not to keep messing with a drive that is failing and just unplug it until absolutely necessary. I admit I didn't realize that before although it does make sense.

I put it aside but just got Diskwarrior and am now running it. Started last night and it is still going on Step 5, "rebuilding directory". I'm getting the "Speed Reduced by Disk Malfunction" message followed by a number. That number has been steadily climbing and is now at 3837.

I have heard that some people have had to run DW for days. So..I don't know...we'll see. Obviously it doesn't bode well for the drive itself. Anyone have any experience with this long phase of DW operation?

Anyway, thanks for all the advice!

 

[ZapNZs]

If DW is giving you that message, there is a reasonable chance that the drive itself is physically failing (at least every time I've seen that DW message, the drive was in fact failing). If the drive is failing, the process can indeed take days, and you may now want to consider using DW's emergency backup feature as opposed to just rebuilding the directory (you access this through the Preview screen, and even if you have bad blocks, it can still recover files.) For that matter, ensuring the other partition is backed up is essential IMO as this drive is done for.

• Did you run the DW SMART module to check the drive by chance? (If you did, did it report any errors?)
• Is the current scan you are running in Scavenge mode? (because you have tried other Apps previously that may have modified the directory, this is the mode you should probably be running in - Alsoft could confirm if this is advisable given the current state of the drive.)
• Have you called Alsoft to explain where you are currently at? (they've been hugely helpful for me when I've had questions on plans of action regarding Mac storage issues)

 

[coxsone]

Thanks! I was running it in scavenge mode - but after a while the whole scan ended up failing (after almost 2 days).
The other partition is definitely backed up. Since it's been the weekend (and a holiday one) I haven't contacted Alsoft. Good to hear that as an option b/c I wouldn't have thought about it otherwise.

ZapNZs: Can you give a little more guidance on how to access the emergency backup feature? The only way I see to access the Preview screen is to start rebuilding the directory.

The partition shows up on the pop up menu under "Directory" but I don't see it come up under "Files".

 

[ZapNZs]

Thanks! I was running it in scavenge mode - but after a while the whole scan ended up failing (after almost 2 days).
The other partition is definitely backed up. Since it's been the weekend (and a holiday one) I haven't contacted Alsoft. Good to hear that as an option b/c I wouldn't have thought about it otherwise.

ZapNZs: Can you give a little more guidance on how to access the emergency backup feature? The only way I see to access the Preview screen is to start rebuilding the directory.

The partition shows up on the pop up menu under "Directory" but I don't see it come up under "Files".

Hit F6 on a desktop keyboard when DW is the front-running App, or FN + F6 on a laptop keyboard, and it will open the Preview window, which you can then use to manually navigate to and copy files from the failing drive to a good drive. If you highlight something and a few seconds later it unhighlights itself, from what I have observed this seems to be because there is insufficient room on the destination to copy the file/folder/set. (Side note - why they do not provide UI access to this feature in the dropdown menu I have no idea considering how DW can mount a drive when other attempts fail making it potentially valuable for such usage. For a long time, I did not even know it existed!)

Should this fail, one other last ditch effort is trying to use Linux. For whatever reason, it seems like Linux reads failing drives better than Windows or Mac. CarbonCopyCloner does a good job at this too, but how useful it is in this case I am not sure. (I am far from an expert on hard drive health so take my advice with a grain of salt!) (Other Sidenote-Similar to what organicCPU noted, I have always used eSATA when rebuilding as it so happens I use eSATA extensively...but I can't say how big of a difference this makes as I am not that technically knowledgable on error correction.)

@DeltaMac has far more experience with DW than I do, and may have some thoughts on this that I missed.