Without knowing when old file data becomes invalid, SSDs expend a lot of write cycles ferrying useless data around. This not only causes normal file operations to slow down, it also means more reading and writing to the flash cells, diminishing their lifespan unnecessarily.
Tip: You may have noticed that even though you buy SSDs of a certain capacity, you have much less space actually available to use. A typical 256GB SSD will have only about 240GB available for use, for instance.
The reason is that SSD manufacturers set aside a percentage of the drive’s space for the firmware to use as a buffer for Garbage Collection and other maintenance tasks. This is called Over-Provisioning and it’s necessary for making sure that the drive’s performance doesn’t degrade significantly as it fills up.
As a general rule, the more free space there is on an SSD, the better it will perform.
By default, SSDs have no way of knowing when files become invalid, and this is where TRIM comes to the rescue.
TRIM is a command that the operating system sends to the SSD telling it which data has become invalid. Using this information, the SSD can perform its Garbage Collection more efficiently, and reduce the strain on the hardware.
Using my example from before, this is an illustration of the same file management scenario, except with TRIM enabled this time around.
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