Does filling up an SSD slow it down?

Discussion in 'Hardware Components and Aftermarket Upgrades' started by WCFire, Mar 27, 2012.

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  1. WCFire

    WCFire Notebook Evangelist

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    I've done Google queries on this subject and seem to get conflicting answers. Conventional HDD wisdom is that filling it up to capacity is bad, but I want to know if this applies to SSD's as well.

    I've heard some sources say that SSD's should not suffer any significant losses from filling it up:
    MPG - Mac Performance 102: Storage - Why You Need More Space Than You You Need

    Browsing forums, however, I've seen people claim that you should not fill up your SSD. I'm thinking that perhaps it depends heavily on the model of the drive? I'd like to know how this would generally apply to SSDs, but specifically I'm looking at the Samsung 830 series and the Intel 320.
     
  2. Greg

    Greg Notebook Nobel Laureate

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    When you use a hard drive up it tends to get more and more fragmented as the OS is constantly reading/writing data. If a hard drive does near full capacity, and it is fragmented, that almost guarantees that you are going to suffer high latency and low throughput since the drive has to constantly access various portions of the disk to do the most meaningless of tasks.

    With SSDs, read/write latency is theoretically (usually) constant across the entire drive. Defrag is no longer needed, and you no longer have to be as concerned with fragmentation of files.

    Where SSDs do have a problem with a nearly full capacity is when you are writing to the disk. NAND cells can only withstand a few thousand writes before becoming damaged. If the drive is almost full, and you are trying to write data to the drive continually, then you run the risk of burning out the unused portion of the drive faster.

    It isn't good to completely fill up either a hard drive or a solid state drive, but the reasons why are completely different.
     
  3. WCFire

    WCFire Notebook Evangelist

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    Thanks, that's good information Greg.

    Is there a % of the drive you would recommend leaving free?
     
  4. tijo

    tijo Sacred Blame Super Moderator

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    For now, i'd keep the drive at a max of 80% full. What Greg didn't mention as well is that the way that SSDs are made, to achieve the high write speeds they have, the memory you are writing to on the SSD has to be empty. Since when you delete data, the OS only marks the space as free (it doesn't actually erase the data), the SSD's garbage collection has to do it's work and erase the NAND memory marked as empty. To perform efficiently, garbage collection, needs a minimum amount of free space on the drive as well which is another reason not to have it full.

    Here's more on the subject: AnandTech - The SSD Anthology: Understanding SSDs and New Drives from OCZ.
     
  5. flipfire

    flipfire Moderately Boss

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    Always have at least 20% free space on SSD and 15% on a HDD. Its just good practice to never fill up any drive all the way.

    Although some SSD controllers can have better low space performance than others.
     
  6. Generic User #2

    Generic User #2 Notebook Deity

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    are you sure you're describing that right?

    what does endurance have to do with speeds before you start to lose significant amounts of cells?
     
  7. tijo

    tijo Sacred Blame Super Moderator

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    What greg posted might not directly have to do with speed, but it's another reason not to fill a SSD, wear leveling only goes so far.
     
  8. Tsunade_Hime

    Tsunade_Hime such bacon. wow

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    I can tell you, my OCZ Agility 2 60 GB in my Vostro 1500 was 80%+ full, and performance has significantly gone down, boot up speed, read/write speeds.
     
  9. jclausius

    jclausius Notebook Virtuoso

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    Except when you use an OS and SSD which both support TRIM. With TRIM fully enabled, a delete should erase cells those cells on disk so they are ready for the next write operation. See AnandTech - The SSD Anthology: Understanding SSDs and New Drives from OCZ

    It seems for SSDs with SandForce controllers more free space is required for the drive not to hit other performance problems. -
    - AnandTech - Intel SSD 520 Review: Cherryville Brings Reliability to SandForce
     
  10. tijo

    tijo Sacred Blame Super Moderator

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    TRIM does alleviate the problem somewhat, but it does not fix things completely, if you abuse the drive at near full capacity, performance will still decrease as was the case for Tsunade's Agility 2. Correct me if i'm wrong, but doesn't TRIM take some time to perform it's operations if you're using the drive somewhat intensively as well?
     
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