It looks as if the failure came from the wiping part. Thanks so much for the quick and easy tip. Worked like a charm for me to reformat an external drive. Is there a way to work around needing a password? You may be able to rectify this issue by booting into single user mode, and then after the fsck scan renaming the home folder back. You really have to tackle one problem at a time. First, figure out your password.
I am trying to format a windows pre-formatted hard drive to use on my mac. I watched the video posted here that says to partition it, but my partition button is greyed out, what can I try next? If it successfully unmounts the volumes, the volumes are unmounted and thus should not show up in Finder. Is there a way to restore the data prior to erasing using the steps above? And what are you trying to do? Get data off the volume before erasing it? Great piece of advice! Worked at first attempt, I was running out of hope after trying several solutions from other forums.
Thanks for the post. Yeah, unfortunately, no idea on that. Honestly, since that appears to be an external drive, I would shut down the computer and then just unplug the drive. I have tried all the methods listed in previous comments. I used to have a boot camp windows 7 that was deleted a year ago If that would effect it. I am not using any external drives. After trying for several hours, came across this solution and it worked perfectly, thanks much for posting this! Either way, glad this worked. How do you know which one to choose to unmount?
Type df -h and hit Enter to see free disk space but this will also show the mounted paths. Why are you trying to unmount Macintosh HD? Are you booting from an external drive? Boot into recovery mode hold down Cmd-R while rebooting and then you should be able to unmount and erase Macintosh HD. Hence this series if inquiries. If you really want to erase the entire disk, including the recovery partition, you must boot from an external drive. Anyway, it sounds like I should be good to go.
Thanks for the help, I really appreciate it. Thank you so much! It took me an hour to find your page and I am glad that I did. You have made my day! Wanted to format it but then it still says it needs an unmounted disk. Hi Ronald, I ran across your post and see you had the same issue im having now with no luck in finding a solution. This was a year ago I realize but do you happen to remember how you fixed your SDcard?
Unable to write to last block of device -… - Apple Community
HUGE help! Formatting the hard drive or partition scheme will recreate a new HFS file structure on the hard drive, which will be free from cryptic errors.
This is the most recommended method to repair the error. Any OS X boot drive is needed to complete the task. But, the important point to remember is that the installer or the recovery drive must reside in the drive, separate from the primary boot disk with the installed OS on it. The above steps offer a resolution of the problem. The errors could have been unresolvable without a boot drive. Therefore, a bootable thumb drive was a good option.
The above error may also be triggered due to first Aid or while formatting a non-boot partition. In this case, a resolution of the problem occurs with the Recovery Partition, which comes with all the newer versions of the Mac OS X. However, this is not applicable for the modification of the boot disk with the help of partitions or formatting. Then the resolution lies in the previous method. Otherwise, we follow the steps:. This will not work with the disk that is throwing the error is the same as the primary boot partition.
3 Ways to Fix ‘Couldn’t Unmount Disk’ Error
The solution lies only in using a separate USB drive for fixing the error. Device failure may happen any time without warning. The loyal external hard drive may not show up or mount in Finder. Imagine how will one access the videos, documents like spreadsheets etc. Thankfully, advanced software such as Stellar Data Recovery Professional for Mac can help you recover data from an unmounted external hard drive. Vishal is a data recovery expert Stellar addressing several data loss scenarios on a macOS system. He loves to read autobiographies and his personal favourite is of Steve Jobs.
View More. Hello, My Macintosh HD is attacked by a virus or malware. I scan with antivirus software and deleted affected files. A large number of files are corrupted. Hi Gilbert, First, restart your mac Sometimes when you turn it back on, everything returns to normal. Secondly, Repair the unmounted Macintosh HD in recovery mode. Third, fixed your Macintosh HD not mounted by the terminal. Fourth, run FSCK command in single-user mode.
Last if have you lost your data so you can recover with the help of Stellar Data Recovery Professional for Mac. Please help me recover as the SSD contains important projects and documents. I suggest you to install Stellar Data Recovery Professional for Mac to recover your important documents and to avoid any data loss risk. Run the following command to attempt to overwrite the contents of the device file which is the contents of the disk.
Note that when this command runs successfully, the cursor will drop to an empty line and wait, instead of returning to the command prompt. During this time, the command will be writing to the disk, so you can wait a few moments and then press Control-C to halt the command. Instead, it just means you ran the command after the system captured the device and got stuck trying to manage it. If you see this error, then do the following:. This will indicate the command has captured the device before the system, and is now overwriting it.
Allow the command to continue for a minute or two before pressing Control-C to cancel it. At this point you can open the Disk Utility program and you should see your drive with no storage volumes available. You can then partition and format the drive to prepare it for use in OS X. It broke when automatically unmounted while copying a VMware Fusion disk image. It may take a few attempts but it should be doable. Alternatively, you can try placing the command in a looping script and then run the script as root, to apply the command as fast as possible:.
When this happens, wait a few moments as mentioned in the article, and then close the Terminal, confirming to cancel running processes. If you simply press Control-C will cancel the command but the script will start it right up again. When this is done, you can then try using Disk Utility to partition and format the disk for use again.
With hundreds of such last line in a row several each second! After about 15 minutes waiting, I unplugged and plugged back the pendrive. Then Terminal stopped not showing mure of such last line no other message shown. After clicking Apply, I got:. Partition failed Partition failed with the error: Disk object invalid or unable to serialize. An then such last error message for all consecutive trials. This command should overwrite the partition table, but if the drive is working then the system should be able to recognize it as blank media and write another partition table to it.
My guess is if wiping the drive like this does not work, then it is likely the drive is beyond repair. The disk4 is the drive pendrive. Before doing what you explained in the article, Disk Utility showed a single volume partition inside the drive. After doing what you said, Disk Utility shows no volumes inside. Yet, I cannot partition the drive. This is what I get when I try to partition it with Disk Utility:. This will ensure more of the drive is overwritten by the command, and possibly allow you to recover it.
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Thanks for your help. I have done as you said. Terminal was indicating hundreds of the following lines in a row several per second :. If then I unplugged and plugged back the pendrive, it stopped showing such message line and the CPU activity was down and no fan heard. But after eight minutes, it started again.
I did that several times. I also left such activity running for about four hours doing nothing else on the Mac. Eventually the Mac rebooted itself! I got the message:. Now the pendrive shows both the drive and the single volume inside on the left pane of Disk Utility, as did before doing what is indicated in your article above. Alert Some information was unavailable during an internal lookup.
If I try to partition the drive, the Apply button is grayed, so I cannot do it before today it was possible, as described above. Using Much information, along with graphic illustrations of all the partitions on a drive. When I was finally stuck with Apple and Gives all of the infor SilverLining did, and better control over partitioning.
You cannot use it on the same drive you are trying to partition or change partition sizes, attempt to activate, etc. Before reformatting a drive that is reporting mount errors, try restarting your computer. I get this kind of error on occasion and restarting will render the drive usable again. I surmise that, in this case, the problem is not with the drive but with the system which has somehow become constipated, for lack of a better word.
Of course if the drive truly is damaged this will not help. My point is that there can be other, less serious, reasons for a drive to become inaccessible or unresponsive and drastic measures should not be the first resort. In my experience, the process of un-mounting and mounting drives and partitions can actually precipitate mount errors which, as I said, can be resolved with a restart.
In a situation like MaX has encountered, while trying strenuously to save a pen drive may have intellectual value, or provide an interesting challenge to an experienced troubleshooter, on the whole the time and effort you expend in trying to resurrect the drive may be more than the replacement cost of the drive. Given that the procedure Topher describes effectively erases the drive, there will be no data to be salvaged and thus the value of the data is not part of the equation.
- Erasing an External USB or Hard Drive that keeps failing in Disk Utility;
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Of course, with a large hard drive this value equation will be different, and a conscientious effort to salvage the drive may be appropriate. Even here, though, one will eventually reach a point of diminishing returns. For this reason they should be used only for temporary storage. In the case of hard drive problems, the best solution is to regularly back up the data on your drives. This way, if the drive truly is broken, at least your data will be safe. Some really conscientious people keep multiple backups and regularly rotate these from older to newer media.
All that said, I will save this article because it offers a solution beyond what most disk utilities offer. Indeed, I have thought before this that such a solution must be available somewhere; I guess it was only a matter of time before Topher uncovered it. There really are some problems for which Terminal is the only solution.
Restarted and voila! I have restarted many times to no avail. Actually, I have been trying to first repair and then format this pendrive for about a year now. But that does not seem to be an easy procedure, depending on the manufacturer, etc. But all that environmental durability is wasted if the drive itself tends to fail.
Have you contacted LaCie about the problem? If anyone knows how to get it working again they should. And, if you replace it, you may want to consider whether you really need such a physically robust keychain drive. So, no joy there. Their parsimonious and short-sighted behavior deserves all the bad news you can spread about them. An attempt will be made to connect this device to the best available host controller. This might result in undefined behavior for this device.
After a few minutes, it shows the Partition window, but after selecting the Partition Layout 1 Partition , the Apply button is grayed and I cannot type inside the Name or Size fields. Any idea on how to repair or format this defective pendrive will be most appreciated. First, XP is very old as operating systems go and may not support the necessary drivers for your USB device.
The default behavior is to use the Apple drivers to access external devices because, in most cases, that is simpler and more transparent. But you can change that setting. If you do, Windows may direct you to download the drivers you need, which means more rooting around on Windows web sites. If you have access to a Windows PC you might get more reliable results with the utilities in question, and it might ultimately be simpler. If you can access the drive on Windows, go ahead and format it Fat The advantage of using Fat 32 is that the drive will also be usable on a Windows PC, supposing that necessity ever arises.
On a side note, most flash drives are formatted Fat 32 because that is sufficient for the smaller sizes flash drives come in. Also, if you could format a flash drive with the newer NTSF format, if would not work on a Mac without additional software. After almost a year, I did it!
How to use, troubleshoot, and repair your Mac
The flashing tool found that it had one bad block probably the first one, which prevented formatting. After flashing it which formats it as well , the pendrive works fine. No Spotlight Index in all cases. Topher, it would be great if you could write an article about it. While Topher may be able to reconstruct what you did in a general way, you are the one who knows the nitty-gritty details of the project.
May I suggest you write it up yourself and then ask Topher to publish it on MacIssues, if not on the main page, then on the forums as a stand-alone topic. The subject certainly begs condensing from the rambling dialog on this thread. And, if you do write it up, I suggest you include links to the sites from which you downloaded the necessary software — the more direct the link, the better. Not everyone will have your skill at sniffing out items on non-english web sites. And finally — congratulations! No doubt the time you spent on this was worth far more than the cost of the drive, but nothing can match the satisfaction of solving such a difficult problem.
Keep up the good work. I am very barely grasping and hanging on to much of what you guys are kicking around.. I have tried to shrink my external drive in disk utility and the power shut down in the process. When I restarted the pc , everything dissapeared. I formated my HDD from hfs to fat. I need to recover all my work. Can you please give me your advice.
By reformatting your drive you wiped out the indexes that tell it where files are on the drive. Your only option for recovering your files would be to use a file recovery tool like DiskDrill, or Prosoft Data Rescue, to scan the drive for file structures and try to recover them. This will likely not recover everything, but should be able to get at least something. Be sure to not use your drive before doing this, as using it will overwrite the data on the drive and make it impossible to recover.
The first thing Andrei should have done before trying to shrink his drive was back it up. Ignoring the possibility that something might go wrong only compounds the problem.