How can I see if Windows 7 is using TRIM for my SSD drive?
According to the Crucial User Forums - Is TRIM Running? to test if TRIM is enabled run the following in an administrative command window.
fsutil behavior query disabledeletenotify
If it comes up as 0 then it is enabled.
Have a read of the comments of Support and Q&A for Solid-State Drives and this Intel Community Forum for more info.
I'm still looking for an authoritative answer, but I noticed that on my machine, automatic defragging is scheduled for all of my HDDs, but not my SSD. I think this means Windows is recognizing the disk as an SSD.
The click-by-click version of the answer:
Right click on a disk drive, go to properties.
Select the Tools tab and click on Defragment now...
Click on Configure schedule...
Click on Select disks...
The SSD should not show up in the list of disks if Windows recognizes it as an SSD.
I wrote a command line program to check if TRIM is enabled:
Download & source code
trimcheck
This program provides an easy way to test whether TRIM works on your SSD. It uses a similar method to the one described here, but uses sector calculations to avoid searching the entire drive for the sought pattern. It also pads the sought data with 32MB blocks of dummy data, to give some room to processes which may otherwise overwrite the tested deteled disk area.
The program will set up a test by creating and deleting a file with unique contents, then (on the second run) checks if the data is still accessible at the file's previous location.
Until there're better answers you can use indirect clues from the latest AnandTech article on SSDs: The SSD Improv: Intel & Indilinx get TRIM, Kingston Brings Intel Down to $115:
TRIM won't work on a RAID array.
(Other information previously here about non-MS drivers not supporting TRIM was out of date. For example, Intel added TRIM in March 2010 provided the drive is not in a RAID array: Intel RAID driver adds pass-through TRIM support )