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eftychia at 12:31am on 2010-03-15Still behind on ... well, life. Behind on lots of projects, behind on LJ/DW/IJ/etc. readiing, obviously behind on posting, behind on email ... Not sure when I'll start to catch up. But in the meantime:
I put the old hard drive from my Mac into a USB enclosure just to see whether it was Completely Dead or Mostly Dead. Well ... Disk Utility can see and identify it, but cannot repair it, nor copy it. Using dd(1) from the command line, I can copy a little bit at a time, then dd stops with an I/O error; starting it again with a "skip=" parameter gets me another chunk, and so on. (I also tried fsck(8), which said the superblock magic number was wrong and couldn't find an alternate superblock on its own.)
So I can apparently read parts of the disk, but what I'm copying will have holes in it.
To try to recover info from the drive more efficiently (or at least more conveniently) -- and/or to try to reconstruct MP3, JPEG, TIFF, and HTML files from the partial-disk-image-chunks, what tools should I STFW for? (Okay, I know I can use strings(1) to search for HTML...) Or is this going to be a yak-shaving exercise where I start by refreshing my fuzzy memory of the structure of an inode and start cobbling together my own tools in C?
A bunch of directories were in my Dropbox folder, so I got those back right away (about 600 MB). Another few gig, I was eventually able to read from the DVD I'd been in the process of burning when the old drive stopped being helpful (I couldn't read it on the Mac's internal optical drive, nor with an external USB DVD drive on the Mac -- I had to attach the USB DVD to a WinXP box and mount it as a Samba volume (once I found out that the Mac's Ethernet port automatically senses when a crossover cable ought to have been used and reconfigures itself accordingly, which is awfully convenient)). But there were a bunch of directories I wasn't able to copy in time, and a couple of those contained files it would be really good to be able to recover.
(no subject)
If it is HFS+, and you can piece together a correct-sized disk image by filling missing areas with nulls, and then copy it to a linux box and loopback mount the file as a disk, you could try fsck.hfsplus on it, but I don't know that it would do any better. It at least would not have hardware errors distracting it...
I'd be curious what the SMART diagnostics on the drive say, but that's probably immaterial, and I have yet to see a usb shoebox that supports it. I would try reading it from a straight IDE controller and not in a shoebox to see if that makes a difference, but it probably wouldn't, although the IDE-USB frobs in shoeboxes can be cheesy.
Good luck... --akb
(no subject)
In other news, the DVD that I thought I'd managed to restore ~/Src and ~/Projects from ... contains a valid directory directory structure and files that look like the right sizes, but each of the files is all NULs. *grr*
Not sure about SMART -- I can't see that, but I don't know whether the drive itself lacks that feature, or the USB enclosure fails to allow access to it.
(no subject)
But the gold standard (IMHO) is DiskWarrior. If you have a place you can do so, image the drive and I'll see if I can attack it when I get back to the area.
(no subject)
I'm guessing that's an Intel binary?
I've got an image I made by sticking together the chunks 'dd' could grab, with blocks of NULs in place of the parts 'dd' couldn't read, on the (fortunately much larger) new drive, but I used a 512k blocksize, so I can probably fill in a little more. (Alas, my first attempt at automating this resulted in an un-killable process -- still debugging that.)
fsck
Additional superblocks may be moot though, because when things were bad enough to trash both my primary superblock and the first alternate (@32), my data was trashed too. And the disk was probably a candidate for replacement.
I save (elsewhere, several elsewheres) the output of newfs as part of my system-config info just for this sort of occasion.
Re: fsck
What i've used for disc recovery...
It seems that they've got a v3 out now, too.
when i had a harddrive that wouldn't mount, I looked around for all the software that claimed it could get everything that "the other programs couldn't" - and they had nothing to prove it. Data Rescue 2 lets you download the entire software for free, and it will run its magic and show you everything it can retrieve. If you pay them the licensing fee ($100), then you can make it happen.
Disc crashes usually happen because the directory gets corrupted. that's where the heads spend the most time, so it makes sense that they'd be the first to go. All this means is that the computer doesn't know where to find the data. Data Rescue reads the entire disc, and then creates a new directory from what it was able to find on the platters. when it worked its magic on my dead drive, I found things I had deleted years before, that hadn't been overwritten yet.
All it takes is a computer to load Data Rescue onto, hardware to connect the dead drive, and a "target" drive to dump the recovered data on to. (I was recovering a 80-gig drive, using a 30-gig laptop, so I got an external drive to throw all the recovered data onto).
So. Download your preferred version of Data Rescue. See if it will do its thing. And if it will, then you know you're in business.
--Benjamin
Re: What i've used for disc recovery...