Apple's built-in disk management utility for the mac. Erases, formats, and restores volumes and drives.

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How to fix the error: “This disk doesn’t contain an EFI system partition”?

I get the following error and cannot start Bootcamp after accidentally deleting the EFI-partition of my main drive. This disk doesn’t contain an EFI system partition. If you want to start up ...
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183 views

Restore on new drive: Time Machine versus “Restore” via Disk Utility

I am about to install a new 240GB OWC Mercury Electra 6G (6Gb/s) SSD into the main drive bay of my MacBook Pro, moving the original Apple-installed 120GB 3G (3Gb/s) SSD into the optical bay using an ...
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1answer
52 views

Backing up a RAID experiencing I/O issues

I recently began working for a company that has an OS X Server with a PROMISE Pegasus Thunderbolt RAID (RAID 5) attached as a file server. Within my first couple of days, it became apparent that users ...
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1answer
232 views

Problems with target disk mode, HD does not show in Finder/Desktop (only in Disk Utility)

I have a MacBook Pro which goes straight to Disk Utility when I try to start it (it totally froze and I forced it off and on). And no luck in repairing the hard disk (Disk Utility can't repair…) I am ...
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3answers
332 views

Mac OS X doesn't recognize hard disk

I replaced my CD drive with a Western Digital 750GB hard drive using the iFixit guide. My Mac for some reason throws error on any interaction with the hard drive, for example on disk utility when I ...
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40 views

Partitions shows it is 2GB when it is actually 120GB

After messing with the partitions to install Ubuntu, the hfs+ partition which I use for my user data went from 130GB to 2GB (OSX is on a separate partition). Disk Utility shows this partition as ...
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77 views

Partition of harddisk lost/unusable

I'm using OS X Yosemite - version 10.10.2. I have 1.12 TB fusion drive on my system. Recently I wanted to make a partition on my system, while making the partition on the system using disk utility ...
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35 views

How to rename disk indentifier?

I created 5 partitions on my portable-drive via DiskUtility. $ diskutil list disk2 /dev/disk2 #: TYPE NAME SIZE IDENTIFIER 0: ...
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164 views

Is undoing Yosemite's CoreStorage conversion dangerous?

I tried to make an 8 GB partition on my hard drive so I could make it into a bootable drive, like Recovery HD but without the need to redownload the OS, but for some reason Disk Utility wouldn't let ...
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46 views

Remove partition and restore the space without erasing

Time ago I split the hard drive (500gb) in two partitions (250 each), now I don't need them anymore, so I have first erased successfully one partition and now I have still the second one (Mac HD 2) ...
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63 views

How does disk utility work while the system is live? (e.g. partitioning/resizing the OSes partition)

How is it that Disk Utility allows you to resize the partition that OS X is botted from live, while the OS is running? Can there be problems doing this? I would have thought that booting into recovery ...
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564 views

Why does Disk Utility show one “Macintosh HD” as a logical drive and another that says core storage physical volume

I am trying to figure out why I have 2 Macintosh HD Drives Appearing in disk utility. One of them i can mount and shows it as being a logical drive and the second one i can't mount but it says it has ...
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147 views

Is my hard drive already dying?

Although everything is working fine with my Macbook Air from Mid-2013, I have a few errors that bother me. Here they are: Onyx says this: The SMART status was not verified because it is not ...
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2answers
250 views

How do I regain unaccessible free space after a failed Boot Camp install on a non-Fusion drive?

Firstly - I know this has been answered, but I am hoping for a more broken down answer, as I am not quite so technically minded, but I can follow instructions! So in summary I have tried to install ...
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23 views

Diskutil can't add drive to mirror

bash-3.2# diskutil appleraid add member disk3 disk8 Started RAID operation on disk8 LookingGlass Unmounting disk Repartitioning disk3 so it can be in a RAID set Unmounting disk Can't write the RAID ...
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1answer
97 views

Flashing folder icon appeared once after changing Macbook hard drive

About 2 weeks ago, I updated my late 2011 Macbook Pro hard drive to a Crucial MX100 solid state drive. The drive installation and data migration went fine with no issues, but today I found the ...
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1answer
232 views

Trying to boot up on Mavericks USB Install Drive, receive prohibited sign on screen

I have a late 2011 Macbook Pro and I had Mavericks, which ran just fine, but I upgraded to Yosemite after hearing some good reviews. I didn't back it up in time machine. It made my laptop extremely ...
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1answer
61 views

Replace Recovery HD with a “bootable drive” formatted partition?

A while ago, I had the idea to use the bootable Mac OS X USB drive-making procedure on a hard drive partition, so that I could basically have a version of the “Recovery HD” that doesn’t need to ...
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249 views

My Macbook Air doesn't recognize my USB

I've always used my USB on this computer. The only issue i would have is that it wouldn't always appear on screen, but i would just eject it and put it back in and it would all be ok. Today for some ...
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121 views

Is there a way to manually repair a CoreStorage volume?

I was playing around with CoreStorage on a test disk and used the undocumented commands cs addDisk and cs removeDisk. The addDisk command worked just fine and was able to expand a logical volume ...
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1answer
48 views

Bootcamp Partition Creation Failure

I wanted to install Windows on my 2011 Macbook Air running 10.8. I had approximately 40 GB of a 120 GB hard drive free and I set Bootcamp to create a 20 GB partition for Windows. Halfway through the ...
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1answer
277 views

Disk Utility not letting me partition my SSD or modify the current ones

Just yesterday I finally got my hands on a MacBook Pro in which I was planning to install Ubuntu and Windows aside from OS X for studying purposes. I was barely beginning by partitioning the disk, or ...
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1answer
65 views

GPT looks valid. Diskutil sees empty disk

External 3 TB disk. Stopped working after a power bump. GPT reports as follows: bash-3.2# gpt show /dev/disk6 start size index contents 0 1 PMBR ...
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1answer
108 views

Flashing question mark, low hard drive space

When I booted my Mac last night I got a flashing folder against a gray background. The computer started fine this morning, but when I closed the lid and opened it up again I had to reboot, and now ...
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272 views

Yosemite 'About this mac' displaying the wrong storage

I am having a strange problem where my 'About this mac' > ' Storage' is showing that I Have 470gb of Apps install on a 250gb SSD. I have used 3rd party disk scanners and they are all showing the ...
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191 views

I can't create a second partition in Mac

When I go to my disk utility, my main hard gives me results like this It's showing capacity 499gb but only remaining 10mb. Now please see the second image What's happening with my Mac?
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313 views

Remove Bootcamp when Boot Camp Assist will not

I purchased an iMac from a buddy and recently upgraded to Yosemite so I am learning as I go about Macs. However, I decided I wanted it to be quicker so I purchased an OWC SSD to install as a primary ...
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1k views

How much data has been written to my SSD over its lifetime?

Is there a Terminal command which will show me how many GB has been written to my SSD through the whole lifetime of the disk? I'm asking because I want to find out how many cycles have been done. SSD ...
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1answer
172 views

re expand a partitioned disk

The internal disk of my Mac book pro is partitioned as follows: % diskutil list /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: ...
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3answers
5k views

“Couldn’t create temporary file.” error when erasing free space on external disk

I was trying to wipe the free space of an external USB 3.0 disk in OS X (Yosemite) disk utility. However, I receive the following error: EDIT: The disk is formatted as GUID / Mac OS Extended ...
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1answer
200 views

Macintosh HD disappeared from finder after “disk damaged and cannot be repaired”

I have a MacPro 13.3 Inch mid2011 with 500GB storage and recently while performing a Mac update, it froze and was still stuck on a grey screen even after multiple restart attempts. I finally tried ...
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1answer
60 views

Mac Encrypted HDD Please help!

Hi everyone I have encrypted a partition of an external hard drive from the mac desktop. I pressed that key button then pressed memorable and it changed my entire password unknowingly. I need help. ...
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566 views

How to add free space to a Logical Volume Group? (Resizing Partitions)

I have two CoreStorage volumes on disk, one is 200GB the other is 50GB. I want to make the 1st 125GB and the second one 125GB. Currently I have been able to use the diskutil cs resizeStack command to ...
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595 views

Resizing and moving OSX partitions in Disk Utility

So, I have a Mac Mini with a 160GB drive (it's an old model but it's only for testing). It had 4 versions of OSX on it but one needed more space so I removed the oldest version (Lion) and want to keep ...
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2answers
66 views

Created a second OS X partition, erased the first, now can't delete old partition

I bought a secondhand macbook pro (early 2011). It was running Yosemite, but I wanted to do a fresh install, as initially I didn't have the password. I created a 2nd partition and installed a clean ...
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2answers
52 views

Resizing Partitions

I cannot resize the HD of a new Mac Mini. The Mac HD shows 700+ GB on one partition with Yosemite on it and another partition of 200+ GB named "Free Space" and I cannot figure out how it got there. ...
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430 views

Orphaned inodes in SSD in MacBook Pro Early 2011

I have a Macbook Pro 15″ Early 2011. Last year I changed the disk to put a new Samsung SSD (Evo). Recently my computer was really slow. I rebooted on the recovery partition, and tested my disk with ...
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93 views

I'm not able to re-size a HD Partition to utilize all its free space, how can I fix this?

I've seen a couple of questions on the exchange that are similar to the issues I am having. But I haven't been able to get things to work referencing those issues. I am ultimately looking to install ...
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1answer
52 views

Free Space Won't Delete [duplicate]

I am running OSX Yosemite. I had free space on my partition, (see picture below) but now it wont delete. I change the format to Mac OS Extended (Journaled), and then when I hit the " + " button it ...
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2k views

diskutil shows Macintosh HD is missing (with Recovery HD occupying the entire space)

So yesterday I managed to screw up my iMac 2012 (with Fusion Drive) by installing the Mac OS X 10.10.2 update... The installation stalled and when I tried to restore from an external drive using Time ...
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49 views

Change write permissions on internal HD outside of OS

I have a late 2009 iMac with a 1TB internal HD. I am unable to boot the OS however when running disk utility, through target boot and booting into an external HD, I am unable to repair, erase, ...
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3answers
725 views

Clear free space in Disk Utility

So I recently removed Windows 7 from my iMac, but Bootcamp didn't let me do it. I used Disk Utility instead. The old Windows 7 partition now shows up as free space. I want to reinstall Windows 7 again ...
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104 views

USB key/disk not identified as a storage device

I have a 64GB USB key that I suddenly can do nothing with...I've tried both Mac and Windows diagnostics, as described below. At this stage I don't mind losing its data (99% of which was recently ...
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2answers
278 views

Flashing folder at start up, all recommended troubleshooting has failed

I really hope someone might be able to help with this cause I am getting frustrated beyond belief. I have a MacBook Pro with Mavericks OS X 10.9. About a week ago it crashed while I was printing, ...
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1answer
236 views

Not possible to create a sparsebundle image on a SMB mounted Volume

I'm trying to create a sparse bundle image from Disk Utility directly on my NAS (through a mounted smb volume): I then get the following error after a few seconds: Creating a sparseimage the ...
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161 views

200GB of lost space! Difference in file size between finder and disk utility

I have installed yosemite and I am trying to have a backup using time machine. Time machine gives an error that the external drive size is not sufficient. And here begins the adventure... I have an ...
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2answers
4k views

I think I messed up the Fusion Drive on my 1TB iMac (with BootCamp)

this is a somewhat similar post to this one (Can't create partition on free space with Disk Utility) but not quite... It started with me creating a BootCamp partition (around 145 GB) for Windows ...
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1answer
1k views

What does “EFI system partition couldn't be created” mean?

When trying to click "Repair Disk" on an external hard drive from Disk Utility, I got the following error message: ... Repairing the EFI system partition's file system Updating boot support ...
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2k views

Partition issues after deleting Core Storage Logical Volume Group. Everything prompts an unmount error. HELP!

I followed the instructions on this link (last answer) to delete the Core Storage Logical Volume Group via terminal while pressing Cmd+R during startup. These are the functions I used in terminal: ...
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1answer
3k views

Can't make more than two partitions

I want to multiboot my MacBook Pro, I'm trying to make partitions but in Disk Utility I can't make my partitions, only can divide by 2? Why? It's a normal SSD not a fusion drive (SSD+HD). Now I'm ...