I recently purchased a new solid state drive (an OCZ Vertex 2 (80 GB)) to use primarily for my operating system. I also have three other SATA hard drives of assorted sizes for long-term data storage. I successfully installed Windows 7 onto the SSD, and everything seems to work fine (I'm still not sure how much faster, I'm still optimizing the system). I am not noticing the speed gains I thought I would get, but that is an other issue entirely.

I was browsing through the Bible of OCZ SSDs, and noticed the following in Section 60-76 - Tweaks and TRIM:

Q. How do I know if TRIM is enabled on my OCZ SSD?

A. In Windows 7, go to start/run/cmd), type the following:

fsutil.exe behaviour query DisableDeleteNotify

It should respond back with:


if TRIM support is ready and active. If it's not, then type:

fsutil.exe behavior set DisableDeleteNotify 0

After a bit of searching on Google, I found similar results elsewhere (set DisableDeleteNotify to 0), which makes sense since for TRIM to work, the solid-state drive needs to be notified when deletes occur (for the garbage collector) unlike a normal hard drive). When I run the query on fsutil, I get the following result:

DisableDeleteNotify = 48

Following the instructions I found, I set this to 0 instead of 48. However, I am beginning to wonder. Is this all the proof I really need that the OS is using TRIM?

Also, since this applies globally for the computer, is TRIM data being sent to the other hard drives connected to the computer? And if so, would this cause any degradation in disk performance?

Also, because I posted the bounty, I want another quick thing answered. This page from Microsoft states how Windows 7 will support it. However, can anyone find a more recent page preferably from Microsoft detailing the TRIM support in Windows 7, and how to ensure that its both enabled & working?

  • Also, I have reformatted a few times, and placed the SSD in two different computers. Each time I query the value of DisableDeleteNotify (obviously before I set it to 0), it's always 48. Jan 7, 2011 at 15:53

3 Answers 3


The SU thread How do I know if my SSD Drive supports TRIM discusses this same question.

This answer remarks that "DisableDeleteNotify=0" means that TRIM is enabled in Windows. This only means that TRIM commands will be sent to the disk driver, which might either ignore it or send it to the firmware, which in its turn will either ignore it or use it to good effect.

So it seems that you have done all that is necessary in Windows. Windows will send TRIM commands to the disk driver. However, there is actually nothing further that you can do to verify that it is actually working. There are no benchmarks or other tests that really test the TRIM functioning of the disk driver or the firmware. If you find in the future that Write operations are too slow on the disk, then this means that it is not working.

You can use any of the disk benchmark programs that are found on the Web, to test disk performance with DisableDeleteNotify set to 0 or 48. Who knows? You might actually find a difference in performance. (I have not found any explanation of the value 48.)

Otherwise, the only thing left to do is to regularly check for new versions of the disk driver and firmware, to keep them up to date as much as possible. If TRIM is not functional at the moment, it will become functional sometime in the future.

To answer your other question: TRIM cannot affect non-SSD drives on the computer. It will be silently ignored by the disk driver or the disk firmware.

I did find also the article Enabling TRIM support in Windows 7 which details a method of finding if the firmware supports TRIM:

Download, install and run the Intel SSD Toolbox. If your drive is not an Intel SSD, the only option available will be "View Drive Information". Click that. Scroll down to Word 169 and look at the value for Bit 0 - Data Set Management Supported. if this is 1, you have TRIM. If 0, you don't.

The article How To check if SSD and TRIM have all windows 7 functions working? also says:

Generally, if you have the SSD hard drive, win7 would disable disk defragmentation, Superfetch, Prefetcher and ReadyBoost features. If you want to check their state, you can use the following steps.

Navigate to the following registry,

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters

If the superfetch and prefetch features are disabled, their registry value should be 0, please check if EnablePrefetcher and EnableSuperfetch are both set to 0.

It also says :

To check if the SSD has been properly detected by looking in Disk Defragmenter.

  1. Open Disk Defragmenter
  2. Click the Configure schedule button
  3. Click the Select disks button

If the disk is missing from the list, then it has been detected as an SSD and will not be automatically defragmented.

  • Thank you for your response, this is the best so far. Besides that blog post, have you found/seen any other Microsoft articles detailing TRIM support in Windows 7? (Also, for completeness of the answer, could you include that quote from the answer you linked? Specifically the second half.) Jan 7, 2011 at 16:00
  • I found some more info, added above, which may help verify if Windows thinks this disk is an SSD and has optimized its parameters accordingly. This doesn't mean that TRIM works.
    – harrymc
    Jan 7, 2011 at 18:08

I don' know if this works but see the The OCZ Tech Wiki and on that page it will tell you if your SSD has TRIM and how to enable it.

  • Yeah, I saw that article before I bought the drive. However, that's for the older Indilinx-based drives (mine is a Sandforce), and I know it supports TRIM. Jan 7, 2011 at 15:52

Yes you do need the TRIM for your SSD let me explain: in regular hard disk when you write a 0 or a 1 on a physical sector the magnetic head just flips the sector and goes on its business, this happens for all changes made to that sector and it doesnt matter is just a flip. SSDs does not have magnetic flips, when you write a to an empty SSD sector that sector gets a 1 or a 0, and the next time something needs to change in it the SSD can't simply flip it, it has to use set it to unused first, once the sector is marked as unused then you can write something on it, this is what TRIM is doing for you, periodically setting the marked as deleted sectors as actually deleted, if you disable TRIM your SSD will slowly lose perfomance because eventually ALL sectors will be used and there will be the need for an aditional operation every time a change its needed. So TRIM only works a sweep guy of sorts, TRIM will not work on regular hard drives because they don't need it. tldr. don't disable it unless you want your SSD to slow down.

  • I know how TRIM works, and I know why SSDs use it. That was not my question. I want to know how I can know if the operating system is sending TRIM commands to the drive. Jan 6, 2011 at 13:46

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