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

351 Comments

View All Comments

  • Sagarf1We - Thursday, April 20, 2017 - link

    If you are trying to put in on the badge, are welcome Reply
  • ultrafine99 - Friday, June 02, 2017 - link

    With this Google play redeem code hack you only have to choose the gift card that you want, http://giftcardsnosurveys.com/ Reply
  • jougenda - Monday, July 17, 2017 - link

    Para cada nivel el juegos My Little Pony en http://littleponyjuegos.com/ es su carácter. Busque toda la última página con los cómics. Prepárense, la chispa, se convirtió enmascarado Matterhorn, está a la espera de que en el primer nivel. Utilizar activamente el poder mágico, en los casos más difíciles flotador sus superpoderes. Reply
  • jackeyroe - Friday, April 22, 2016 - link

    Great, that what you said I agree and I think that all your opinion are nice and smart for me. If you want any sports shoes you can feel free to my website and I will share you coupon code. And for your this opinion of SSD might I know that is it possible for my website, if it is possible I will try to find is there any more tips that could improve all the functions of my sports shoes site. If it works then will be my pleasure and I will share the great article to all my kind friend, they will be happy to share it into the network of them. Would you please take a look to my website firstly:
    http://www.kicksvovo.com/
    Reply
  • davidsmith123 - Thursday, July 07, 2016 - link

    That sure was a lot to take in! Fantastic article though, it has really opened my eyes to the possibilities that Solid State Drives provide. Probably wont be buying one in the immediate future given the so-called depression and such things, but i will certainly keep up with SSD progress.
    Thanks again for your fantastic articles - im sure im not the only one who really appreciates them :)
    http://www.hubnames.com/
    Reply
  • devdeepc - Friday, September 02, 2016 - link

    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 Reply
  • hapeid - Wednesday, January 25, 2017 - link

    Hy Anand.

    I wanted to compliment you on what I think was an excellent article. This is the type of thing I really have always liked from Anandtech. The detailed background, the technical reasons for the issues and then a thorough review of the current state of things.

    I just finished upgrading my desktop. The only remaining item I wanted to replace was the hard disk. I had been thinking about getting a Velociraptor but instead I just ordered a 60GB Vertex from Newegg.
    Thank you.
    Reply
  • DHIAN - Friday, January 06, 2017 - link

    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.servicekomputerbali.com/ Reply
  • Rahul Ji - Sunday, August 21, 2016 - link

    Dear KadensDad, these drivers fail all the time. With the new technology and new softwares coming , everyday some drivers and some softwares go outdated. This ought to happen. But, what will not go outdated is our Microsoft xbox live codes at http://xbcodejunction.com . These codes work anywhere anytime, anybody can use them. Just so easy to get and use. So come and try your copy for free. Reply
  • giyan - Friday, January 06, 2017 - link

    This is good for car tool ,and also needs software http://www.forobd.de/.i think it is helpful for me! Reply

Log in

Don't have an account? Sign up now