disk utility not verifying mac HD

Something is wrong with the hard drive. Next time try Repairing instead of Verifying. Tell us what Disk Utility reports.

Do this:

Repair the Hard Drive and Permissions - Yosemite, Mavericks, Mountain Lion or Lion

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears.

Repair

When the recovery menu appears select Disk Utility and press the Continue button. After Disk Utility loads select the indented Macintosh HD entry from the the left side list. Click on the First Aid tab, then click on the Repair Disk button. If Disk Utility reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit Disk Utility and return to the main menu. Select Restart from the Apple menu.

Boot to the Recovery HD:

1. Restart the computer.

2. Immediately after the chime press and hold down the

"COMMAND" and the "R" keys together.

3. Release the keys when the Utilities Menu appears.

You don't really need it. I used it for several years, but found that I didn't need it because the OS took care of itself without help.

You are welcome. Not really necessary. To some extent, the OS defrags itself based on what I have read.