When is SSD TRIM active?

When is TRIM active? I mean this happens when the computer "idles" but what is meant by "idle". I asked at the Corsair forums regarding the Nova that's in my netbook and they said that TRIM occurs only when powered on but logged off.

I've never seen that documented anywhere. I'm also curious when the drive garbage collection and wear leveling is active. I know this happens when the drive is "idle" as well, but again, what is meant by "idle"?

 

TRIM is an ATA info command sent to the drive. It is 'information' that the controller can use. It has nothing to do with the actual moving, rearrangement, erase or anything like that. It helps the controller to update its 'free map'.

 

All about TRIM and SSD's from Microsoft's engineers: Support and Q&A for Solid-State Drives - Engineering Windows 7 - Site Home - MSDN Blogs

 

I know that, but when does it occur, and more importantly, when does GC / wear leveling take place?

 

the information gets sent when ever something changes in the file system.

the ssd processes that information immediately, but can schedule flash cleanups how ever it wants. afaik the intels respond about instantly to it. but i bet they buffer some cleanup jobs.

 

That is a controller policy thing. One way is that if a TRIM results in a whole erasable block being free, it would erase it immediately as well(so the next write may be able to use it). Another way is just let a timer based routine to do it in batch manner. There are so many way to implement the GC/wear leveling. And why different controller can handle different work patterns.

 

Thank you. So the Corsair rep is full of crap then?

 

yes, of course. the ssd does not know anything about your pc. once it's running (after the bios), all it gets from your pc "there, store that. there, free that. there, store that". it can't know if you're logged on or not, if you run an app, not even what an app is. it knows nothing about the rest of the world. complete blackbox.

what i guess is, their disk only cleans up while not having had some accesses for a while (no read? no write? no clue!). thus logonscreen.

 

davepermen is correct.

You can think of the SSD being a network server which your PC communicate to. It has its own mind of when and how to manage its space. Even modern HDD is in some way doing this but HDD is a much simpler device, in this regard.

There are lots of 'they think they know everything because they sell it' guys out there, OCZ support staff is a typical example.

BTW, that is also the reason I don't like SF drive. According to them(OCZ or Corsair), periodic logout is kind of a routine that is needed to give its GC the chance to do its job(I am not sure if they are right or wrong). Which is a total change to my work pattern(when I don't use my computer, I put it to sleep and I never logout, just lock).

 

I was gonna say, I never log out. I just let it sleep or power down.

 

me, too. when my pc's on, it's in use. another reason why i chose intel. some are stated to not do any gc for like 20 minutes after the last write. there would be no gc for me in those cases, ever.

 

Yeah, and I can't find details on any SSD's actually. But as much as I've used my Intel 80GB it's performance has not dropped and it's been installed on three different machines so far.

 

I'm convinced that the idle @ login screen (for "15-25 hours/week" as suggested to me by OCZ support staff) causes higher overall power draw when compared with a traditional HDD