External Hard Drive corrupted?

Discussion in 'OS X El Capitan (10.11)' started by eighteentwelve, Nov 14, 2015.

  1. eighteentwelve macrumors newbie

    Joined:
    Nov 14, 2015
    #1
    I accidentally knocked my external hard drive off the table and it became unplugged. When I tried to connect it again, I put in the password, and received a: "The disk you inserted was not readable by this computer message." When I did First Aid for the overall hard drive, it was successful, but when I tried this particular partition, it said: "The First Aid process has failed. If possible, back up the data on this volume." The second partition on the hard drive, which was not connected at the time it was unplugged, works normally. Is there anything else I could try?
     
  2. DeltaMac macrumors 604

    DeltaMac

    Joined:
    Jul 30, 2003
    Location:
    Delaware
    #2
    Accidentally unplugging your external, along with slamming to the floor, while it is mounted, is never a good idea. Sometimes you get lucky, but often the disk platter gets physical damage, and there is little you can do.
    You could try a couple of different hard drive utilities.
    Good choice would be Disk Warrior. or maybe Data Rescue, or Disk Drill.
    One (or more) of those should fix you up, or offer the "good" news that your hardware is damaged, and might not be reparable.
    Or, moving on, there's a couple of good utilities used on Windows that more thoroughly test your drive, possibly even repairing the damage, such as Spinrite.
    Or, there's commercial data recovery services that will do whatever is possible to get everything you want from a damaged drive. And, you pay through the nose for that. The data better be truly important.
     
  3. getrealbro macrumors regular

    Joined:
    Sep 25, 2015
    #3
    Your disk issue may be due to physical damage because of the fall (as suggested by DeltaMac) or it could be as simple as a corrupted directory because the disk was detached without being able to update the directory.

    FWIW I recently “lost” a partition and Disk Utility told me the same things it is telling you. But if I waited long enough, the partition would eventually mount and allowed me to recover nearly all of the data by using the Finder to copy the data onto another external drive. I used the Console app to monitor the fsck_hfs.log to tell me what was going on while I waited for the fsck_hfs process to complete and the partition to mount.

    If you do get the partition to mount, do NOT try to make any changes. Treat it as read -only.

    —GetRealBro
     
  4. eighteentwelve thread starter macrumors newbie

    Joined:
    Nov 14, 2015
    #4
    Thank you for your help.

    The floor was less than two feet away and is carpeted, so I don’t think the fall did anything. I’m planning to buy Disk Warrior today, but I tried the Data Rescue trial last night, and I was able to see most of my files. From what I read online, I wasn’t expecting them to still be organized with their names. Does that mean anything? There’s also a new folder called Orphaned Files.

    Also, do you know if the the good partition is safe to use, or is it better to just buy a new hard drive? Sorry if these are stupid questions. I don't know a lot about computers.
     
  5. getrealbro macrumors regular

    Joined:
    Sep 25, 2015
    #5
    I would buy a new disk and partition it like the current one. You could then copy all of the data from the good partition to one of the partitions on the new disk. Then recover the data from the bad portion to the other partition. Copying the data from the good partition to a partition on the new drive verifies that the data is OK and moves it to a safe place at the same time. The other partition on the new drive gives you a safe place to recover the data to.

    Once everything is a good as you can get it on the new drive, you can repartition it which places a new blank directory in all of the partitions. Depending on your willingness to take risk. You could just put it back in service for other tasks, use it as a double backup drive, use it as a scratch drive that holds data you wouldn’t mind losing, or donate it to Goodwill who have people that refurbish/recycle electronics.

    ——GetRealBro
     
  6. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #6
    I believe the problem you're having is software-related, as distinguished from hardware-related.

    Ever since the advent of USB drives, I've noticed that they seem to be particularly susceptible to this kind of "damage" when accidentally disconnected without first removing the icon from the desktop (and thereby updating the drive directory).

    In the "old days" of the Mac, back when one connected via SCSI, Apple's "HDSC setup" app (equivalent of today's Disk Utility) had the ability to re-install disk drivers. But Disk Utility has no command, and I wonder if this is even possible with USB unless you re-initialize a disk.

    Here's something to try if you haven't done this yet.
    Do this in the EXACT order presented.
    1. Power down everything (computer and drives) all the way off
    2. Disconnect problem drive
    3. Reboot computer
    4. Connect problem drive
    5. Even if both partitions don't "mount right up", LET IT SIT FOR A WHILE
    I think the Finder will try to repair the problem partition, give it 5-10 minutes before giving up. No guarantees, but sometimes this can work with a damaged partition.

    What you try next depends on what was ON the partitions of the drive.

    If you can "afford to lose" the data on the first partition, you could copy everything on the second partition to another drive, and then try a compete re-initialization of the problem drive....
     
  7. getrealbro, Nov 16, 2015
    Last edited: Nov 16, 2015

    getrealbro macrumors regular

    Joined:
    Sep 25, 2015
    #7
    For those interested in some of the details...

    This isn’t just a USB issue. It happens to FireWire drives too. It occurs because when a disk is “unplugged” before it is “unmounted” by the Finder, OS X does not get a chance to update the drive with the latest changes in the directory. This makes that partition's “FILESYSTEM DIRTY”.

    Every time a partition is mounted, OS X runs fsck_hfs to check the file system. If everything is OK the log looks like this…

    /dev/rdisk0s3: fsck_hfs started at Mon Nov 16 15:28:42 2015
    /dev/rdisk0s3: /dev/rdisk0s3: ** /dev/rdisk0s3 (NO WRITE)
    /dev/rdisk0s3: Executing fsck_hfs (version hfs-304).
    QUICKCHECK ONLY; FILESYSTEM CLEAN
    /dev/rdisk0s3: fsck_hfs completed at Mon Nov 16 15:28:42 2015

    If not, the log looks something like this…

    /dev/rdisk2s3: fsck_hfs started at Fri Jun 13 21:32:52 2014
    /dev/rdisk2s3: /dev/rdisk2s3: ** /dev/rdisk2s3 (NO WRITE)
    /dev/rdisk2s3: Executing fsck_hfs (version hfs-226.1.1).
    QUICKCHECK ONLY; FILESYSTEM DIRTY
    /dev/rdisk2s3: fsck_hfs completed at Fri Jun 13 21:32:52 2014

    /dev/rdisk2s3: fsck_hfs started at Fri Jun 13 21:32:52 2014
    /dev/rdisk2s3: /dev/rdisk2s3: ** /dev/rdisk2s3
    /dev/rdisk2s3: Executing fsck_hfs (version hfs-226.1.1).
    /dev/rdisk2s3: ** Checking Journaled HFS Plus volume.
    /dev/rdisk2s3: The volume name is Seagate 3T
    /dev/rdisk2s3: ** Checking extents overflow file.
    /dev/rdisk2s3: ** Checking catalog file.
    /dev/rdisk2s3: ** Checking multi-linked files.
    /dev/rdisk2s3: ** Checking catalog hierarchy.
    /dev/rdisk2s3: ** Checking extended attributes file.
    /dev/rdisk2s3: ** Checking multi-linked directories.
    /dev/rdisk2s3: ** Checking volume bitmap.
    /dev/rdisk2s3: Volume bitmap needs minor repair for orphaned blocks
    /dev/rdisk2s3: ** Checking volume information.
    /dev/rdisk2s3: ** Repairing volume.
    /dev/rdisk2s3: ** Rechecking volume.
    /dev/rdisk2s3: ** Checking Journaled HFS Plus volume.
    /dev/rdisk2s3: The volume name is Seagate 3T
    /dev/rdisk2s3: ** Checking extents overflow file.
    /dev/rdisk2s3: ** Checking catalog file.
    /dev/rdisk2s3: ** Checking multi-linked files.
    /dev/rdisk2s3: ** Checking catalog hierarchy.
    /dev/rdisk2s3: ** Checking extended attributes file.
    /dev/rdisk2s3: ** Checking multi-linked directories.
    /dev/rdisk2s3: ** Checking volume bitmap.
    /dev/rdisk2s3: ** Checking volume information.
    /dev/rdisk2s3: ** The volume Seagate 3T was repaired successfully.
    /dev/rdisk2s3: fsck_hfs completed at Fri Jun 13 21:51:58 2014

    The fsck_hfs process that attempts to correct the problem can take several minutes. In the testing that I was doing after Mavericks was released (see above), the Segate 3T drive took nearly 20 minutes to finally mount. So patience is a virtue.

    In more severe cases the disk may mount with a warning that you should “back up everything you can ASAP” or words to that effect.

    —-GetRealBro
     
  8. eighteentwelve thread starter macrumors newbie

    Joined:
    Nov 14, 2015
    #8
    Thank you the responses. I tried waiting, but the partition never mounted. I’m still trying to decide between Disk Warrior and Data Rescue. From what I’ve read, Disk Warrior seems like the better option, but I know from the trial version that Data Rescue can get most of my files. If Data Rescue can access them, is there a pretty good chance Disk Warrior will be able to do so as well?
     
  9. getrealbro macrumors regular

    Joined:
    Sep 25, 2015
    #9
    I wish I could help you decide. But it has been at least 3 years since I used both products when my trusty PowerBook G4's disk failed due to physical damage. IIRC they had a very different look and feel but accomplished the same level of file recovery.

    I’d go with more current reviews.

    —GetRealBro
     
  10. Rodan52 macrumors regular

    Rodan52

    Joined:
    Sep 21, 2013
    Location:
    Melbourne, Australia and Bali, Indonesia
    #10
    eighteentwelve, try doing a web search DiskWarrior Vs. DataRescue so long as it's not a site connected to the products ie an industry comparison site you may find your answer there.
     
  11. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #11
    OP wrote above:
    "Disk Warrior seems like the better option, but I know from the trial version that Data Rescue can get most of my files. If Data Rescue can access them, is there a pretty good chance Disk Warrior will be able to do so as well?"

    You must understand that these are completely different applications with completely different purposes.

    DiskWarrior repairs and rebuilds disk directories.
    That's all it does.
    If the drive has directory damage, DW -may- be able to reconstruct the directory and get it going again.
    No guarantees that this will work. But it might.
    But even if DW fails to get the partition mountable, the data may "still be there".

    That's where data RECOVERY software like DataRescue comes in.
    DR doesn't care (much) about a disk's "directories".
    On the contrary, it's designed to work when the directories are corrupted, or even if they are completely "wrong" (see example I provide later).

    How data recovery software works, and why it works:
    Even with a bad directory (or NO directory), the data itself can "still be out there" on the platters and sectors of the drive.
    DR software can "ignore" the directory and "go right to the platters".
    It harvests whatever fragments it finds and then re-assembles it onto a "scratch disk" (this is why you need ANOTHER drive to do data recovery).
    One proviso about data recovery is that you will often lose all previous folder hierarchies and many (or most) of your previous file names.
    This creates extra work, but the consolation is that you GET YOUR DATA BACK.

    Generally, with a data recovery program you do this:
    1. You download the app, "aim it" at your problem drive, and let it run
    2. The data recovery apps scans the drive (can take quite a bit of time) and then puts up a report with what it has found
    3. The app will let you recover -ONE- (and ONLY one) file, as proof that it can work for you.
    4. At this point, you pay the registration, get a code, enter the code, and the app goes to work on the recovery.

    Finally, a personal experience.
    Like the OP, I once had a partition on a drive "disappear" on me.
    I couldn't bring it back with Disk Utility or other "drive repair" software.
    It looked to be "gone for good".
    How did I get it back?
    I RE-INITIALIZED the ENTIRE drive into ONE partition (yes, "re-initialized").
    This wiped out all the previous directories and partitions, and put a fresh set of disk drivers onto the drive.
    IMPORTANT IMPORTANT IMPORTANT:
    I DID NOT "zero out" the drive, only did a quick initialization.
    If you zero out the drive, YOUR DATA WILL BE GONE.
    I then ran DataRescue on it, looking for "mp3" files (the files that had been lost).
    It took a little time, but DR found all the lost files.

    Of course, many files had lost their filenames. How to get them back?
    I created (on ANOTHER, separate drive) a new OS install, and moved the recovered files there.
    I then opened iTunes -- fresh with no iTunes library yet created
    I dumped all the loose files into iTunes.
    iTunes read the file metadata (which is part of the individual files and NOT part of the old directory which got wiped out in the re-initialization), and re-assembled the files into albums, artists, etc.
    This worked for the vast majority of the files!

    But that's how I got files back, from an otherwise "unrecoverable" drive....
     
  12. Jimpsgami macrumors newbie

    Joined:
    Feb 8, 2016
    #12

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