How many hours of use should my disk have before I replace it?

We recommend that you replace older disk drives even if they have not failed. As disks age, the chance that they will fail increases. It is always better to replace a disk before it fails than to wait for it to fail and have to restore data from a backup or replace a disk on a Mac which is currently in use.

SSDs: most SSDs (Solid State Disks) contain wear indicators which show how much longer they can be used. These count down from 100% of media life remaining down to 0%. An SSD should be replaced once its media life remaining is less than 10%. The media life remaining for a particular SSD is shown in the disk tile in the SoftRAID application. The SoftRAID Monitor will also warn you if any SSD has less than 10% media life remaining. This feature is not supported by SSDs shipped by Apple.

Laptop disks: we recommend that disks in laptops be replaced after 5,000 hours of use. These disks are smaller and less reliable than the disks found in desktop computers and servers. This amount of use corresponds to 2–3 years of use by an average user.

Disks in desktop computers: we recommend that disks in desktop computers be replaced after 10,000 hours. While these disks are more reliable than the smaller ones in laptops, they are subjected to the repeated stress of being turned on and off. This number of hours corresponds to 4–5 years of use in an average office environment.

Disks in servers: we recommend that disks in servers be replaced after 20,000–25,000 hours. These disks are usually properly cooled and are not subject to the stress of being turned on and off but they often experience periods of intense activity. This number of hours corresponds to 2–3 years of use in a server which is on 24 hours a day. These recommendations are corroborated by the Google study on disk failure in servers which showed that disks fail at a rate of 2–3% during the first year and 7–10% during the subsequent years.