Disk Utility failure: The faults of disk utility make Macintosh HD not mounted.

Hard drive failure: If the drive is physically damaged because of a head crash or component failure, that also makes the drive non-mounted.

Sometimes, the damaged file system of the hard drive can also make the hard drive non-mounted in the Finder.

Corrupted File system: There is also the possibility that the drive is corrupted because of logical errors, bad sectors, etc.

It is also possible that the cable connecting the drive to the Mac is damaged or non-functional.

Connector: If you are connecting hard drive to your Mac through the USB port, the port can be faulty.

Failing to do so can also make Macintosh HD not mounted.

Preference: To make your drive visible on your Mac desktop or finder, it is necessary to set it in preferences.

When you are unable to view the hard drive on the Mac, it can be due to various reasons: But why disk does not mount, let's find out the various reasons for it. There is a high possibility that Mac won't turn on if Macintosh HD not mounted. It is also possible that your Mac stops working. As the hard drive becomes inaccessible, except the erase button, all other operations become disabled or are greyed out.

If you are unable to view the Macintosh hard drive in disk utility, here the disk is not mounted. All this is possible only if the hard drive is detectable. It can be done by selecting the disk and clicking on the mount link. You can even manually mount the disk if it is not accessible by the computer. If the computer is working, the disk is visible in the left pane of the Disk Utility. When a drive is available for reading and writing operations by the operating system, it is referred to as disc mounting. What does it mean to mount a disk on Mac? Before learning further let's first understand what does it mean by disk mount and disk not mount.

Sometimes the hard drive fails to mount because of various reasons and prevents you from using the system. Macintosh HD or Mac hard drive is the primary storage medium for Mac users.

Part 4: Tips against Macintosh HD Not Mounted.

Part 3: How to Recover Data from Unmounted Macintosh HD?.

Part 2: How to Fix Macintosh HD Not Mounted.

Part 1: Overview of Macintosh HD Not Mounted.

Run disk utility mac single user mode