The Trim Command: Coming Soon to a Drive Near You

We run into these problems primarily because the drive doesn’t know when a file is deleted, only when one is overwritten. Thus we lose performance when we go to write a new file at the expense of maintaining lightning quick deletion speeds. The latter doesn’t really matter though, now does it?

There’s a command you may have heard of called TRIM. The command would require proper OS and drive support, but with it you could effectively let the OS tell the SSD to wipe invalid pages before they are overwritten.

The process works like this:

First, a TRIM-supporting OS (e.g. Windows 7 will support TRIM at some point) queries the hard drive for its rotational speed. If the drive responds by saying 0, the OS knows it’s a SSD and turns off features like defrag. It also enables the use of the TRIM command.

When you delete a file, the OS sends a trim command for the LBAs covered by the file to the SSD controller. The controller will then copy the block to cache, wipe the deleted pages, and write the new block with freshly cleaned pages to the drive.

Now when you go to write a file to that block you’ve got empty pages to write to and your write performance will be closer to what it should be.

In our example from earlier, here’s what would happen if our OS and drive supported TRIM:

Our user saves his 4KB text file, which gets put in a new page on a fresh drive. No differences here.

Next was a 8KB JPEG. Two pages allocated; again, no differences.

The third step was deleting the original 4KB text file. Since our drive now supports TRIM, when this deletion request comes down the drive will actually read the entire block, remove the first LBA and write the new block back to the flash:


The TRIM command forces the block to be cleaned before our final write. There's additional overhead but it happens after a delete and not during a critical write.

Our drive is now at 40% capacity, just like the OS thinks it is. When our user goes to save his 12KB JPEG, the write goes at full speed. Problem solved. Well, sorta.

While the TRIM command will alleviate the problem, it won’t eliminate it. The TRIM command can’t be invoked when you’re simply overwriting a file, for example when you save changes to a document. In those situations you’ll still have to pay the performance penalty.

Every controller manufacturer I’ve talked to intends on supporting TRIM whenever there’s an OS that takes advantage of it. The big unknown is whether or not current drives will be firmware-upgradeable to supporting TRIM as no manufacturer has a clear firmware upgrade strategy at this point.

I expect that whenever Windows 7 supports TRIM we’ll see a new generation of drives with support for the command. Whether or not existing drives will be upgraded remains to be seen, but I’d highly encourage it.

To the manufacturers making these drives: your customers buying them today at exorbitant prices deserve your utmost support. If it’s possible to enable TRIM on existing hardware, you owe it to them to offer the upgrade. Their gratitude would most likely be expressed by continuing to purchase SSDs and encouraging others to do so as well. Upset them, and you’ll simply be delaying the migration to solid state storage.

Free Space to the Rescue Restoring Your Drive to Peak Performance
POST A COMMENT

308 Comments

View All Comments

  • KadensDad - Tuesday, October 27, 2009 - link

    How do these drives fail? I have heard that they will just suddenly die, no more writes or reads possible. What I would like to know is what happens when it dies? Do you lose all data? Just can't write anymore? How does the OS respond? Any early warnings? What about e.g. CRC? How does possibility of data corruption compare to traditional SSD? What about RAID? Since the drives are electrical, not mechanical, this reduces the number of failure vectors and environmental concerns (e.g., ambient temperature over lifetime of the drive). Won't SSDs therefore fail closer together in time in a RAID configuration? This reduces the window of opportunity for fixing an array and also decreases the applicability of RAID, however marginal.
    Reply
  • Dewend - Friday, March 04, 2016 - link

    My partner and i also were seated for lunch, whenever i mentioned to her that I read a script each and every morning newspaper, therefore i chosen to do a little research. Thankfully, I stumbled upon this website, which helped me discover why people consider even thinking about this. http://followersteam.com Reply
  • Askipod - Thursday, November 17, 2016 - link

    This is cool! Your website is great Hey Your information is astounding!! I will recommend it to my brother and anybody that could be attracted to this topic. Reply
  • Askipod - Thursday, November 17, 2016 - link

    WOW. I am very glad to join this comunity and enjoy your article. Your article shared me so interesting information here, looking forward to your update. http://www.nasze.media.pl/pisanie-tekstow-jako-spo... Reply
  • echtgeld - Monday, January 16, 2017 - link

    http://echtgeld-casino.net/ - beste online casinos site Reply
  • SecXploded - Saturday, February 25, 2017 - link

    Exactly. you’re very kind of us about comment - <a href="http://www.nohumanverification.com">www.no... Reply
  • SecXploded - Saturday, February 25, 2017 - link

    Exactly. you’re very kind of us about comment - www.nohumanverification.com Reply
  • SecXploded - Saturday, February 25, 2017 - link

    Exactly. you’re very kind of us about comment - http://www.nohumanverification.com Reply
  • Askipod - Thursday, November 17, 2016 - link

    It's actually a cool and useful piece of information. I am glad that you shared this helpful information with us. Please keep us informed like this. Thank you for sharing http://www.nasze.media.pl/porozmawiajmy-o-pieniadz... Reply
  • seotab - Monday, January 02, 2017 - link

    If you ever thought of enjoying android apps and games on desktop or laptop, then prepare to experience with emulator on Windows. You may also like to get http://appsxpo.com Reply

Log in

Don't have an account? Sign up now