TECH SUPPORT & TECHSPLANATIONS

EXPERT ADVICE

Our resident genius solves your Mac and iOS problems

Email Mac|Life at ask@maclife.com

Get official documentation at support.apple.com| Get help with hardware at support.apple.com/repair

Could your SSD outlive you?

WE’RE USED TO hard drives wearing out. Spinning thin platters at high speed isn’t a good way to a long life. Solid– state drives (SSDs) don’t have moving parts, but their blocks of flash memory have a limited life, set by the number of times they get erased and written to.

Although drive manufacturers are coy about telling us how long SSDs should last, nearly 10 years ago testers took six small SSDs and drove them through erase– write cycles for 18 months before they could finally write no longer. Provided your Mac has a decent–size SSD and doesn’t thrash it because it’s using virtual memory heavily, you should see anything from 50 to 100 years life from it.

In practice, though, most are expected to die through old age after about 10 years.

> How much free space?

How much free space do I need on my Monterey startup disk?

This depends on how much of it will be taken by snapshots, cache and virtual memory (VM) files. Although these can normally be dispensed with when the need for free space is pressing, they can block updates and installations that need large amounts of temporary storage.

Updating macOS uses hidden volumes which could require an absolute maximum of 40GB at their peak. Assuming that Time Machine’s backup snapshots will never exceed 5GB in any 24–hour period, and VM and cache requirements are no larger, the free space required comes to around 60GB for the Data volume on your startup disk.

To that you must add your own allowance to ensure that you’ve got headroom to use that drive, taking it perhaps to 100GB. You can get away with much less, but will be at risk of not being able to update macOS or install a new version of a large app such as Apple’s Xcode.

There are definite benefits from sizing solid–state drives (SSDs) larger so as to maintain ample free space. As the working life of an SSD is largely determined by the number of times its storage gets erased and rewritten, high write loads on a small SSD will reach the write limit more quickly than the same load on a larger SSD.