Os x disk utility updating boot support partitions
Not to worry, our friends, because OS X lets you launch a standalone version of Disk Utility from your Mac’s built in recovery partition.
In other words, OS X’s Recovery Mode gives you a chance to repair a malfunctioning startup disk that prevents your Mac from booting properly.
As noted above, the free tool that widely used for this purpose in OS X Mavericks and earlier is not compatible with El Capitan and Yosemite, so we'll start by walking you through a method that works with OS X 10.10 and 10.11 (in very slightly different ways).
(There are also occasions when a recovery partition won't help.
Type your admin-level account password when prompted, and press Return again.
If you see the message 'To continue we need to erase the disk at /Volumes/Untitled.
It's quite a drastic and time-consuming approach, however. You'll need an 8GB or larger removable drive that hasn't got anything on it you need, and admin privileges. Connect the removable drive to your Mac, and make sure it's called Untitled - rename it if necessary.
Make sure the El Capitan installer (or at least a copy of it), called Install OS X El Capitan.app, is in its default location in your main Applications folder (/Applications).
Use Recovery Mode to: Tip: If the Recovery partition itself has been damaged, enter Internet Recovery Mode instead by pressing Command (⌘) – Option (⌥) – R at boot time.
The built-in recovery partition on your Mac’s startup disk contains recovery tools, like Disk Utility.
Recovery Mode makes it easy to repair your Mac’s disk in situations when the machine won’t boot properly and load the desktop in the first place.1) In the Apple menu, choose Restart.2) As your Mac restarts, hold down the Command (⌘) – R combination immediately upon hearing the startup chime and hold the keys until the Apple logo appears.3) Select Disk Utility and click Continue.4) In the sidebar, select the volume you wish to repair.5) Click the First Aid button.6) Click Repair Disk.7) Two things will happen: either the app will report that the disk appears to be OK (or has been repaired) or you will need to do one of the following: If your Mac’s disk is physically damaged, it will likely need replacing.
Click download and then follow the procedure listed above for El Capitan.
The steps above apply to the two most recent versions of Mac OS X, but there are script tools available that make the process easier if you're running something earlier.
We've got a separate article showing how to create a Mac recovery disk.) Read next: How to reset a Mac: restore your Mac to the original factory settings Generally the best and simplest method is to reinstall OS X entirely. To format the drive, go to Applications Utilities and open Disk Utility. (The name of the disk needs to be "Untitled", if the Terminal commands below are to work, so rename it if necessary.) Select Mac OS Extended (Journaled) as the format type. We've got full instructions on how to do that here - How to make a bootable Mac OS X install drive - but we'll run through the basics again.