Disk Utility is an App made by Apple that allows you to format and repair your disk drive. Not all drives purchased from an electronics store for instance are properly formatted to work with your Mac. The same goes for drives that say they are compatible with both PC and Mac, if you are planning to use that drive solely for Mac it’s best to format it to the more preferred Mac format.

Understanding the Different Formats

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Format Choices

There are a few different formats that work with Mac, Mac OS Extended , MS-DOS (FAT) and ExFAT. With the help of other applications like Tuxera for example, you can also format an NTFS volume.

If you are formatting a drive that you intend to use solely for your Mac the best choice in the Mac OS Extended (Journaled). This is the default choice that all Macs come setup as. The (Journaled, Encrypted) can be used for extra security by setting up a password that will be required every time the external or internal disk drive is mounted. Be careful however, forgetting this password will cost you all the files on the drive.

The Mac OS Extended (Case-sensitive, Journaled) should only be used when you know what you are doing. For most cases you should not use this format as it may cause apps to be faulty, among other issue. This is mostly because of the different way in which the Case-sensitive format works. The default Journaled format recognizes “file.txt” and “File.txt” as the same file if it’s in the same folder location. The Case-sensitive will recognize them as separate files. Many applications are not built to work with this file system and will simply not work or in other cases, even install.

MS-DOS (FAT) is a format that works on both Mac and PC, however it is severely hampered by its 4GB file size limitation.

ExFAT is like a powered up version of MS-DOS (FAT), it does not have the 4GB file size limit and runs faster.

NTFS is like a powered up version of ExFat that adds more security, speed, better disk space utilization and journaling, among other features. However Mac OS X does not natively support NTFS as a 3rd party application like Tuxera will be needed by your Mac in order to write to it. Mac OS X can not be installed or run on an NTFS formatted partition.


Formatting a Drive with Disk Utility

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Format a Disk Drive

Once you’ve decided on the best format for your needs, open Disk Utility. It can be found in your Applications/Utilities folder or in Launchpad. Select the drive that you want to format and click on the “Erase” tab.

This is where you want to be really careful, double check to make sure you’ve selected the correct drive. Formatting will erase everything on the disk!

Beside “Format:” select the format you want to format the drive to. Give a name to the drive and then click the “Erase…” button. A progress bar will appear showing the time remaining. It usually doesn’t take that long at all.

There are certain applications that allow you to restore some if not most of the information on a formatted disk. If you want to securely erase everything on the drive there is also security feature which overwrites the drive multiple times. The most secure setting overwrites the data 7 times.


Repair Disk and Disk Permissions

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Repair Disk

If you’ve ever gotten a message on your Mac saying that your drive has to be repaired or that it can’t be read, then you may be able to repair it with Disk Utility. Although if you ever get an error of the sort pertaining to a failing hard drive, it also a really good idea to make a backup of all your files immediately.

Open Disk Utility, select the drive to be repaired from the left side panel. Select the “First Aid” tab and then click the “Verify Disk” button. Your drive will be checked for any problems, if it finds any click the “Repair Disk” button. Disk Utility will then attempt to repair any issues it finds.

From past experience I’ve found if there is ever an error that Disk Utility can not fix then formatting sometimes fixes the issue. Of course make a backup first. If the drive still is getting errors even after formatting, it may be time to purchase a new hard drive.


Disk Permissions

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Repair Permissions

Getting a disk permission error message can be caused by quite a few things. Some of the most common reasons why your permissions could stop working properly are improper shutdowns, 3rd party application installs, dragging files to and from external drives and sudden loss of power resulting in an improper shutdown.

To repair the disk permissions, open Disk Utility, select the drive and then click the “First Aid” tab. Click “Verify Disk Permissions” and your Mac will start checking for errors. If it finds any, click “Repair Disk Permissions”.

Is the option to repair disk permissions greyed out? Only the boot volume (drive that Mac OS X is installed on) can have its permissions repaired. If for some odd reason you can’t repair your disk permissions on your boot volume then boot from Recovery HD (Hold ⌘R on Boot). Once it’s booted into Recovery Mode open Disk Utility and select the drive, then repair the disk.


Stellar Volume Repair – A more powerful Disk Utility repair app

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Stellar Volume Repair

Is repairing with Disk Utility not fixing the issue? Stellar Volume Repair is a more powerful repair application that checks for errors in the catalog file, multi-linked files, extents overflow file, journaled files, volume bitmap, and volume information.

Two things that make Stellar Volume Repair stand out there is that it can roll back a volume to its previous state and it can be used to create a bootable DVD. The bootable DVD feature alone is extremely useful if your Mac won’t boot up or needs its boot volume repaired. Basically what it will allow you to do is boot from the DVD instead of your Macs hard drive (since the drive is the problem). Once booted into the DVD you are able to repair the drive.

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Limited Reports

Unfortunately Stellar Volume Repair lacks in documentation of what’s happening, it doesn’t have any way of showing you what needs fixing or even what has been fixed. Also unlike Disk Utility, there is a no way of simply checking if there are issues are not, it simply jumps straight into fixing errors.

The best way to use it is to open Disk Utility, select the desired drive and click the verify button. This will show if there are any errors. After that go to Stellar Volume Repair and repair the drive, then back to Disk Utility and click the verify button again to see if the errors have been fixed.

It does seem to be able to fix more errors than Disk Utility and it’s ability to repair the boot volume is extremely useful. All in all, if Disk Utility can’t handle the situation or you need your boot volume repaired then give Stellar Volume Repair a go.

There is a trial version available, however the trial version is limited. You’ll be able to create a bootable DVD disk, but to actually repair the volume you’ll have to purchase the software.