Installing OSX: file system verify or repair failed
<p>After I've pressed cmd + R at start up, I try to reinstall. It takes about 20 minutes before I get an error saying:</p>

<pre><code>file system verify or repair failed
quit the installer to restart your computer and try again
</code></pre>

<p>I've tried to First Aid through Disk Utility, but then i get this error:</p>

<pre><code>First aid process has failed. if possible back up the data
on this volume. Click done to continue.
</code></pre>

<p>And Disk Utility Erase gives this:</p>

<pre><code>The disk disk1 couldn't be ejected
Couldn't unmount disk.
Operation failed..
</code></pre>

<p>Does anyone know the solution to this? My mac has been freezing and bugging out a lot lately, so I'm very much looking forward to a clean slate.</p>