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The Shad Guy Author

Level 3

656 points

Can't Open my Backup DMG years of data gone

Okay I'm going to try to describe this in as much detail as I can and hopefully someone out there can help. I'm using a Mac Pro that has one harddrive in it, 250gb. I also have a Macbook Pro. I also have an external USB drive that's 250gb, and it's partitioned in 2 parts, on is about 200 and the other is 50. I can NOT boot from this drive.

A couple of days ago I decided I would back up my Mac Pro in anticipation of Leopard. So I booted into the Tiger Install disc that came with my computer, and used the disc utility to create a restore image of my entire Harddrive, using the default settings. The image is saved to my external drive.

I got Leopard on Friday and installed it using a clean instal, erasing everything on my computer and installing it fresh. The install went fine and Leopard works magically on this machine. I decided it was time to start bringing my files over from my image I had created, so I attached my drive and opened the DMG, but it wouldn't open, giving me error -4960. PANIC ENSUED. I also tried to mount it on my MacBook Pro which is still running Tiger and I got the same error!

The next day (yesterday) I called Apple, and the man I spoke with told me the reason why it won't mount is because its a raw restore image and what I'll have to do is restore it using the disk utility again. That made sense to me. This morning I tried restoring the image with both the Leopard utility and the Tiger one as well (booting off the install DVDs, that is), but no matter what I do, I get the same error -4960!!

So at this point I'm basically shattered. I live on my computer, it's my whole life (I know that may sound sad haha but it's the truth). This is like having my house burn down, and on top of that, the IRONY of the situation is just too much. The whole reason for upgrading is to get Time Machine.. Ugh. Anyway, Im starting to run out of ideas here. I think maybe it could be because my external drive is a piece of crap or something, so I'm currently copying the thing over to my internal drive and I'll try that. Other than that, I'm thinking the image must be corrupt or something, does anybody know any hardcore tools that could be used in such a situation? Any terminal-fu that could possibly fix this whole problem? I did use data recovery software on the drive yesterday and managed to get a few things, I think,, but I havent really looked through them and it's really not the same as having the files themselves, you know? But I guess it's something.

So yeah, if ANYONE has any ideas on what to do, you have no idea how thankful I would be to hear it.

Jason

touch fuzzy, get dizzy

Posted on Nov 4, 2007 9:20 AM

Best reply

MJWeb

Level 1

125 points

Posted on Nov 4, 2007 10:06 AM

I'm very sympathetic to your situation and have been investigation error -4960 for you. These aren't specific answers but they might point you in the right direction, on your own, or communicating with Apple. Both of these, though unrelated, suggest the problem and solution is related to the User account. Just a hunch, but I'd try opening the DMG from your Guest Account. Keep bugging Apple, too!

http://docs.info.apple.com/article.html?artnum=93311

http://www.tech-archive.net/Archive/Mac/microsoft.public.mac.office.entourage/20 05-02/0052.html

View in context

85 replies

nahnoryb

Level 1

4 points

Nov 7, 2007 2:11 PM in response to nobody loopback

please note that if an option is not in the man page, it is highly like that the option may change behavior or even disappear in a future version of the OS.

so don't plan any mission critical operations based upon this.

byron
not in any official capacity

nahnoryb

Level 1

4 points

Nov 7, 2007 2:35 PM in response to nerowolfe

Don't jinx it 🙂 A good surgeon is always just "cautiously optimistic".

That being said, until I get a look at the image, there is little I can, or should, say about it at this point.

The Shad Guy Author

Level 3

656 points

Nov 7, 2007 3:31 PM in response to nahnoryb

Okay Mr Han, I can see you have some nice credentials! Anyway, I'm glad you're on board for this.

To update everyone, Apple contacted me as of today, and there are some senior people "in the know" who I guess are reviewing the case which is just FANTASTIC news ^_^ so I'm doing all I can with them and help from this board so maybe we can find a solution.

Right now I don't have much space left on any of my drives but I ordered a 500gb drive from tigerdirect.ca today which should be here shortly, that will give me scratch space. In the mean time I'll hang on to this one copy for now (copy of the image that is) until I can get more space for everything.

The following is mostly in reply to you, Byron, but of course to anyone else too. The image is a compressed dmg of my boot partition (that is, when I made the image I used the default type of "compressed").

Mac-Pro:~ jasonbrennan$ hdiutil imageinfo ~/Desktop/MACPROBACKUP.dmg
hdiutil: imageinfo failed - error -4960

Mac-Pro:~ jasonbrennan$ hdiutil udifxmldet ~/Desktop/MACPROBACKUP.dmg
"/Users/jasonbrennan/Desktop/MACPROBACKUP.dmg" has 35073934 bytes of embedded XML data.
The XML data is uncompressed.
hdiutil: udifxmldet: XML data from "/Users/jasonbrennan/Desktop/MACPROBACKUP.dmg" is corrupt.
Conversion of data failed. The file is not UTF-8, or in the encoding specified in XML header if XML.
hdiutil: udifxmldet failed - Not a directory

Mac-Pro:~ jasonbrennan$ hdiutil udifderez ~/Desktop/MACPROBACKUP.dmg
hdiutil: udifderez: could not get resource fork of "/Users/jasonbrennan/Desktop/MACPROBACKUP.dmg": Not a directory (-4960)
hdiutil: udifderez failed - error -4960

And as I've previously mentioned, when I used the DiskUtility from the Tiger Install DVD, it made the image without giving an error.

And in case I haven't posted this elsewhere in the thread, when I try to do a "verify" or repair in Leopard's DiskUtility, I get this error in the log window:
2007-11-07 18:16:05 -0400: [DUDiskController viewablePartitions] expecting DUDisk, but got nil

We can do this!

nahnoryb

Level 1

4 points

Nov 7, 2007 4:16 PM in response to The Shad Guy

Thanks. More instructions are forthcoming in your other communication channel.

I will be sending you a tool to extract the embedded resource fork directly so that I can take a look at it.

I appreciate your forebearance with this matter and apologize for any inconvenience that you are suffering. And furthermore, greatly appreciate your help in debugging this issue.

nahnoryb

Level 1

4 points

Nov 9, 2007 12:32 AM in response to The Shad Guy

Update

I've asked for and received a fragment of the image file, specifically the damaged XML "resource fork".

There is corruption in three different locations which means that there WILL be some data loss.

I am in the process of hand-editing this XML in an effort to create a patched XML which will hopefully at least allow the image to be mounted and as much data can be copied off and minimizing the amount of data loss.

No root cause has been identified.

Thank you for your patience.

nahnoryb

Level 1

4 points

Nov 12, 2007 12:37 PM in response to The Shad Guy

This may be a bit technical, but thought it might be interesting to give some behind-the-curtains insight into the recovery effort.

The UDIF disk image contains various "resources" which can be contained in a several different ways, including a real resource fork or encoded in a bit of XML included inside of the disk image's data fork. Some of these resources ('blkx') form a sort of "memory retrieval index" which maps sections of the disk image file to various "virtual blocks" on the disk that the disk image is supposed to represent.

I examined the XML portion of the disk image which contained corruption which prevented it from being properly processed. I excised the damaged portions of the XML which allowed the XML portion to be read in and the 'blkx' resources could then be loaded. Excision had to take place very carefully as the resource data is encoded using base64 encoding which means that excising the damaged portions of the XML needed to take place on 4-byte boundaries and the amount excised had to be in 4-byte multiples.

After excising the damaged XML, the 'blkx' resource was not usable straightaway as some areas of the index were damaged. I wrote a little tool to edit this structure directly and after some careful manually reconstruction, I believe that I have reconstructed a new 'blkx' resource which minimize the amount of data that will be lost.

Presently, I am awaiting getting access to a copy of the damaged disk image so that I can attempt to install the "prosthetic XML" and then attempt to copy the data off of the disk image.

nerowolfe

Level 6

13,090 points

Nov 12, 2007 12:58 PM in response to nahnoryb

Hey man, there is no off switch on the genius machine 🙂
I am simply a passive obvserver here, but I have great respect for talent and stick-to-it-tivity.
I am sure that you actually enjoy this and look at it as a challenge.
Kudos

Message was edited by: nerowolfe

Nov 13, 2007 3:08 PM in response to nahnoryb

nahnoryb,
Thank you for that insight in your efforts.
That sounds very good - better then my rather rude efforts to acess the data.

Is there a change, that your work somehow will be commited back to the OS ? Some sort of disk-image repair/extract option ?

Do you have an Idea why the image was damaged ?

3 days before, I had a machine, which, prior to an 10.4 upgrade, refused to make an uncompressed image of the disk. It did not lock up, but the imageing process halted.
I then just saved the user profile by copying using the finder.

When I tried to install 10.5, by upgrade/archive and install/clean install the Machine always stopped the installation with an error that some data could not be read from the source.
I replaced the DVD (this was a MacbookPro) with a Harddrive based image - still unable to install, now, I got errors about problems writing some files.
Finally I tried to zero the disk, which also stopped
Replaced the harddrive.
The next attempt to install 10.5 went further, but near the end of the installation again a read error stopped the install.
Now, I replaced the RAM module.

Installation was sucessful after this.

When DiskUtility makes an Image of a disk/folder, do you know, if it makes any sanity checks of the copied data ?

nerowolfe

Level 6

13,090 points

Nov 13, 2007 3:40 PM in response to nobody loopback

nobody loopback wrote:
When DiskUtility makes an Image of a disk/folder, do you know, if it makes any sanity checks of the copied data ?

Whether it does or not, like any backup, the first thing to do is test it while it's still possible to fix it.
I discovered this when I created a backup clone on my external drive. When I tested it, it booted into a new Tiger. Apparently either permissions got messed up or files were missing or both. That was with Silverkeeper. When I switched to SuperDuper it worked and tested perfectly.

MJWeb

Level 1

125 points

Nov 14, 2007 8:33 AM in response to nahnoryb

I have observed this thread from the get-go and I commend your kindness and expertise. We're rooting for you, Shadguy!

The Shad Guy Author

Level 3

656 points

Nov 14, 2007 12:47 PM in response to MJWeb

Hi all, just a little update from my end. First, I'm ecstatic to hear that news from you, Byron, it's just wonderful that we should likely be able to get some/most of my data back. It sounds tremendously complicated what you are doing but also very interesting at the same time. I think maybe there should be a warning message in Disk Utility that instructs the user to verify the image him/herself to ensure integrity. Enough of that soapbox, though, I just really want to thank you for all of your effort so far, this really is a Miracle on 34th Street instance.

And to everybody else, thanks for your support, it really has helped me out a lot and I've certainly learned a few new tricks. My external drive (which contains a copy of the image) was shipped off to Apple yesterday so soon Byron should have direct access to it and we can go from there!

PS: I got more storage yesterday too (same courier dropped off the new drive as picked up the external, huh.) so now I've got more copies of the image just to keep it extra safe.

Nov 15, 2007 6:34 AM in response to The Shad Guy

Good Luck!

MJWeb

Level 1

125 points

Nov 15, 2007 8:52 AM in response to The Shad Guy

"I got more storage yesterday too (same courier dropped off the new drive as picked up the external, huh.) so now I've got more copies of the image just to keep it extra safe."

Well, at least you got some new hardware out of this! 😉

The Shad Guy Author

Level 3

656 points

Nov 15, 2007 2:34 PM in response to MJWeb

Yeah but thats an extra 110$ on top of the 79 I payed for Leopard :P And between work terms, it's tight. Oh well.

nahnoryb

Level 1

4 points

Nov 15, 2007 3:04 PM in response to MJWeb

Just doing my job.

Actually, like most Apple engineers, our time is incredibly over-subscribed with feature work and bug fixes. It is a nice change to actually work directly with a customer!

Surgery is commencing...

Can't Open my Backup DMG years of data gone