Monitor disk health

The Health monitor displays whether your disk is functioning properly and how much of its operating resources remain. To check health of your disk, open the Menu, click the Storage monitor, and view Health.

Most importantly, the Health monitor provides immediate reports on critical failures as they occur. With these early warnings, you'll have enough time to back up or transfer your data to secure storage.

The percentage shown in the Health monitor – the health rate – reflects your disk's remaining operating resources. This resource, or disk lifespan, is determined by critical parameters such as data retention, the condition of memory blocks, and others.

Unfortunately, the health rate can't predict the exact number of months or days your disk will continue to function. However, as a general rule: the lower the health rate, the sooner you may need to repair or replace the disk.

The following clues help interpret the health rates:

• Normal (70–100%)

  Your disk has used only a small portion of its resources and doesn't report significant errors. Most memory blocks are functioning correctly, and there are no evident risks to your data.

• Warning (less than 70%)

  The disk is showing signs of aging and may occasionally report minor issues, such as failing memory blocks. The disk automatically addresses these by re-allocating data from faulty blocks to reserved healthy ones. Failing blocks are a common occurrence in both hard disks and solid-state drives.

  At this stage, disk replacement isn't necessary. However, we recommend making regular backups to protect your data.

• Critical

  The disk is reporting critical errors or has nearly exhausted its available resources, such as healthy memory blocks. Also, this rate is shown when the available spare capacity of the SSD is less than its available spare capacity threshold.

  Note

  Available spare capacity (availableSpare) and available spare capacity threshold (availableSpareThreshold) are the SMART attributes set by the disk manufacturer.

  availableSpare represents the reserve blocks of memory set aside by the manufacturer to replace bad or worn-out memory cells over time. As the SSD experiences wear, these spare blocks are used to maintain performance and prolong the drive's lifespan.

  availableSpareThrehsold specifies the minimum level of available spare blocks required to keep the drive functioning properly. When the number of spare blocks falls below this threshold, it indicates that the SSD is nearing the end of its usable life and may need to be replaced.

• Undefined (–)

  The monitor failed to get the system information required for calculating the health rate.

  If the health rate isn't displayed for your disk, refer to troubleshooting.

Will my disk fail immediately? That's often the first question when you see a critical health warning or a health rate of zero. The answer is: most likely not, but failure could happen soon.

At a critical health rate, diagnostic reports suggest that the disk has either reached the end of its projected lifespan or lacks the healthy memory blocks necessary for safe operation. While the disk may continue to function for a time, the risk of critical failure is high.

So, what should you do?

• Back up your data immediately.

  You can follow detailed instructions on how to back up using Time Machine.

• Have your disk repaired or replaced at an authorized Apple service center.

• You can also use Disk Utility to repair some software-level errors. Disk Utility is a tool that comes pre-installed with macOS.

However, when your disk health is critically low, fixing errors at the software level isn't a reliable solution. Only a service center or repair shop can ensure your disk is in good condition and that your data is secure.