I communicated with a customer regarding an issue with his internal hard drive.  He had Drive Genius 3 installed on his Mac and DrivePulse (feature of Drive Genius that monitors the hard drive for errors) notified him that he had hard drive errors on his MacBook and he needed to repair it ASAP!

Trouble-shooting and Diagnosing Hard Drive Errors

He tried running Integrity Check and then Verify on his drive but got a error.  He told me the error and it seemed that the hard drive was busy.  I asked him to start up his Mac from the Drive Genius 3 disc and then try to run the repair on the internal boot drive.  The repair option is not available when you have started up from the internal drive.  In order to unmount a start up drive you have to start up from a secondary drive.  Most people try running Verify because the repair option is not available when booted from the drive that you need to repair.

Repairing the hard drive

In this case since his Macintosh HD was his primary startup volume, he must startup from another device in order to run the Repair.  He had a Late 2011 model MacBook Pro and he did have a Clone Backup of his hard drive.  He was able to startup from the Clone, open Drive Genius 3 and run the Repair on his Macintosh HD.  He was glad that he was able to fix the error and thankful that DrivePulse detected the problem before it became a more serious issue.
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