SSD Garbage Collection and TRIM explained

[Oleg34]

This article explains everything about SSD Garbage Collection and TRIM. http://www.thessdreview.com/daily-n...ion-and-trim-in-ssds-explained-an-ssd-primer/

Also this website has a lot of info on SSDs. http://www.thessdreview.com/

 

[Quartz-1]

Great finds, thank you.

 

[Aesma]

The article doesn't go into too much detail and is even misleading when showing a big part of a non trimmed drive as available for garbage collection. Without trim, once the drive has been written once in its entirety, there is very little space available for garbage collection. The article says why :

In the case of an SSD, it only becomes aware that the data is deleted (or invalid) when the OS tries to write to that location again. At that time the SSD marks the old data as invalid and it writes the new data to a new physical location.

The SSD cannot know that data is stale until you try to write on it.

There is no mention of the overhead of the whole thing, which is what really interests me. How much space is used by the SSD to store a database of all the blocks ?