I am using the Intel Solid-State Drive Toolbox to view an SSD drive. This utility has an option to manually run "TRIM". What I found odd is the utility reports "The selected Intel SSD has no partition letter. This feature requires a partition letter to run."
I have the disk mounted as a junction point. I hope this is a limitation of Intel's utility, or does Windows 7 TRIM require a drive to be assigned a drive letter in order for it to work?
The way trim works, is that it is the hint to the SSD to indicate which address areas is not being used to contain data. This allows the SSD to optimize internally (usually save work being done by "garbage collection").
when there is no partition on the drive, generally it means that everything is "trimmed". This may not be the case if the SSD wasn't made aware of that. So in this case, I think it's the tool, unable to figure out what it could and could not trim and may just want to avoid trimming unintentionally.
Aside from that fact, the trim feature is specific to ATA protocol. Meaning, it's a command sent to the drive at the lower level so it's not tied to Windows 7 or an application. It's open for anything that is will and able to send the command.