Techtool Pro will work with solid state drives (SSDs), but due to the differences in how SSDs operate compared to traditional rotational hard drives, we do not recommend using the Volume Optimization tool with SSDs.

The main difference between SSDs and traditional rotational hard drives is the way they write data. When writing new data to an SSD block, the existing data must be deleted first, which can slow down the writing process on sectors that have old data not yet overwritten. SSDs that come with Macs have TRIM support, which helps the operating system efficiently manage erased data, improving future write operations.

Additionally, each sector on an SSD has a finite number of write cycles, so it’s more efficient to write to “empty” sectors and to distribute writes evenly across the drive. Functions like Volume Optimization, which repeatedly write to the disk, can be problematic. These functions cause the drive to erase and write over the same sectors repeatedly, which can shorten the lifespan of the SSD.

Volume Optimization was helpful for traditional rotational hard drives because it reduced the distance the drive heads needed to travel, making reading and writing more efficient. However, SSDs have no moving parts (no heads) and write to all sectors at the same speed, regardless of their physical location, making optimization unnecessary and potentially harmful for SSDs.