Is the internal SSD wearing out?
Q Is there a reliable way to check whether my Mac’s internal SSD is wearing out? by DAVID WRIGHT
A Although macOS does monitor the condition of internal storage using SMART status indicators, the most information it gives about this is in Disk Utility, where it simply reports the disk status as ‘verified’, which is of no help in assessing SSD wear.
There are two ways to estimate wear in an SSD. One is to check the disk’s SMART health indicators such as Life Percentage Used, which should be available for all recent Apple internal SSDs. The other is to work out what proportion of its life has been used according to the amount of data written to the drive. For either of these you’ll need a third-party app such as DriveDx from bit.ly/ mac378drivedx.
Each storage unit in an SSD can only be written to around 10,000 times. That means that a 500GB SSD can have 10,000 x 0.5TB written to it before it’s likely to fail through wear. If the indicated Data Units Written is 1,000TB, then it’s roughly 20% of the way through its life.
Both of those options are also available for most Thunderbolt disks, but not for those connected by USB, which require a free kernel extension installed before their SMART indicators can be read.