It took a long time for Apple to finally say goodbye to hard drives as an internal storage medium. But since the switch to Apple Silicon towards the end of 2020, it has been clear: there will never be new Macs with an internal hard drive again. Solid-state drives differ in many properties from rotating magnetic disks, which remained the preferred form of mass data storage for a long time. One question in particular concerns users when purchasing a new one: How long can I use the storage medium before it gives up the ghost? Howard Oakley uses his iMac Pro, which he has used every day for a good seven years, as an example and calculates how long the integrated SSD should theoretically continue to work. The size of the integrated permanent memory makes calculations easier: his iMac Pro has a 1 TB SSD installed. A maximum of 3,000 write cycles is usually assumed for SSDs. So you should be able to write at least three petabytes to a one terabyte SSD before problems could arise. But how much data does a Mac realistically write per day, month or year?
SSD internal statistics
Practically, SSDs independently log how much data they have written so far. Software like DriveDx or Oakley’s free Mints read the information; on the basis of this you can calculate the approximate write load. Oakley says it has been using its iMac Pro every day since December 2018 and rarely turns it off. His SSD reports a total of 150 TB of written data. This corresponds to around 21 TBytes per year or 60 GBytes per day.
Write cycle reserve: 133 years
This means that after seven years, his intensively used Mac has only used up five percent of the guaranteed 3,000 write cycles. With consistent use, he calculates that his iMac Pro should last around 133 years. Of course, other effects are likely to come into play beforehand, which can affect the permanent memory or the computer in general. In any case, he concludes, his iMac Pro is unlikely to reach the limit of maximum write cycles.
Tip: Don’t skimp on RAM
In order to minimize write cycles, Oakley recommends using as much RAM as possible. His iMac Pro has 32 GB of RAM, which means that macOS practically never outsources RAM components to the SSD. For this purpose, macOS uses a separate APFS volume called VM (short for Virtual Memory). If the active programs exceed the RAM capacity, the system automatically swaps the memory contents of inactive apps there. With just 8 GB of RAM and a small SSD, an intensively used Mac can reach the maximum number of write cycles much faster.
The evaluation of a Mac mini M1 with 8 GB of RAM: 83,735 GB have already been written to the 500 GB drive. The maximum write capacity should be 1,500 GB.
Second tip: Leave enough space
Oakley also recommends keeping at least a tenth, and preferably a quarter, of the system SSD free. The background: An SSD full to the brim with unchangeable content would mean rapid wear and tear of the remaining sectors. Although there are load balancing mechanisms that prevent this effect by reallocating inventory data, this also means additional write cycles. To prevent this, you should move large media collections to external SSDs, such as the photo library, local music or film collection. Stored on an external SSD, media collections relieve the load on the startup volume. There are now docks with NVMe slots for the Mac mini M4, which also meet higher write and read rate requirements.
