Hey, There’s an Elephant in the Room

When the first X25-M reviews went live a few people discovered something very important, something many of us (myself included) missed and should’ve addressed: the drive got slower the more you filled it up. It’s no great mystery why this happened, but it seemed odd at the time because it went against conventional thinking.


LegitReviews was one of the first to spot the SSD slowdown phenomenon, good work Nate.

It’s worth mentioning that hard drives suffer from the same problem; just for a different reason.

Hard drives store data on platters; the platters rotate while an arm with read/write heads on it hovers over the surface of the platter and reads data while the platter spins. The diameter of the platter is greater the further out on the platter you go, that’s just how circles work. The side effect is that for the same amount of rotation, the heads can cover more area on the outside of the platter than on the inside.

The result is that transfer speeds are greater on the outer sectors of the platter than on the inner ones. OSes thus try to write as much data to the outer sectors as possible, but like beachfront property - there’s only a limited amount of space. Eventually you have to write to the slower parts of the drive and thus the more full your drive is, the slower your transfer rates will be for data stored in the innermost sectors.

Fragmentation also hurts hard drive performance. While modern day hard drives have gotten pretty quick at transferring large amounts of data stored sequentially, spread the data out all around the platter and things get real slow, real fast.

Randomness is the enemy of rotational storage.

Solid state drives aren’t supposed to have these issues. Data is stored in flash, so it doesn’t matter where it’s located, you get to it at the same speed. SSDs have +5 armor immunity to random access latency (that’s got to be the single most geeky-sounding thing I’ve ever written, and I use words like latency a lot).

So why is it that when you fill up a SSD like Intel’s X25-M that its performance goes down? Even more worrisome, why is it that when you delete data from the drive that its performance doesn’t go back up?

While SSDs are truly immune to the same problems that plague HDDs, they do also get slower over time. How can both be true? It’s time for another lesson in flash.

Why You Should Want an SSD The Anatomy of an SSD
POST A COMMENT

251 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
  • 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
  • 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
  • adsmith82 - Monday, September 14, 2009 - link

    I need to run HDDErase on an X25-M. No matter what bootable CD or flash drive I create, HDDErase does not see either of my SATA hard drives. I already disabled AHCI in BIOS. Also, I am using version 3.3. I know that 4.0 does not work with the X25-M.

    Can someone help me troubleshoot this please? Thanks.
    Reply
  • gallde - Thursday, June 11, 2009 - link

    You point out that TRIM will only work on deletions, not on overwrites. But, couldn't a smart controller look at blocks that have a majority of invalid pages and "trim" them as well, recovering clean pages as a background process? Reply
  • forsunny - Thursday, August 13, 2009 - link

    Why not just make the SSDs capable of individual page erases instead of blocks? Problem solved. Reply
  • Ron White - Sunday, August 31, 2014 - link

    Erasing the NAND transistor in an SSD requires such a large jolt of voltage that it would affect surrounding transistors. Reply

Log in

Don't have an account? Sign up now