What is a Fusion Drive’s working life?
How long should the 2TB Fusion Drive in my iMac last?
Apple’s Fusion Drives are replaced as a single unit, though they are made up of separable hard disk and SSD parts, so the life of the combination is going to be the time to whichever fails first.
Normally, you’d expect that to be the hard disk, as those usually suffer earlier mechanical failure, often after three to five years or more. But Core Storage, the software that manages Fusion Drives, puts less–used data on the hard disk, extending its life. If your Fusion Drive is powered up all the time, high–stress spin–up and spin–down events will be infrequent, and it could last well over five years.
However, Core Storage works the SSD harder than you’d expect a larger ‘pure’ SSD to undergo. SSDs normally fail after about 10 years anyway, but also have a limit to the number of times each block can be written to. Some have found their SSDs have worn their way through that number earlier than they anticipated, even though macOS includes wear leveling and TRIM software to even use out across the whole SSD.
Unless your Mac runs hot, or you do a lot of disk–intensive work, a 2TB Fusion Drive should last rather longer than the three to five years of a typical hard disk, but less than the 10 years or more expected of an SSD. With the cost difference between Fusion Drives and SSDs continuing to fall and become more reasonable, seriously consider getting an SSD when buying a new desktop Mac, provided you can afford it.