On 05/07/2013 10:49 AM, Stroller wrote: > > On 6 May 2013, at 21:07, Randolph Maaßen wrote: > >> - When a file is deleted the file system marks the block device >> sectors as free and sends the TRIM command to the SSD and the SSD >> really frees the underlying cell / breaks the cell - section allocation. > > So if I'm writing a new filesystem, I have to make sure it make the TRIM > systemcall, otherwise it'll break with SSDs?
Not exactly. What the TRIM system call really does is give the drive hints about where the boundaries of your data really are, so that it knows what parts of the disk's space it can take more liberties with. As a rough analogy, imagine you're helping a friend fill a bunch of crates. Perhaps the friend told you he doesn't really care about some of the stuff, and you realize you can get stuff done more effectively by dumping a crate full of junk into the trash and putting other stuff (stuff he cares about) into it. This helps improve disk lifetime and efficiency, but it's not strictly necessary for functionality; nobody's truly harmed by having a crate of junk hanging around, since the owner can always replace stuff in it at their leisure, anyway. It's just more efficient if the crate's empty when he goes to put stuff in it.
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