TRIM Performance

Plextor calls their garbage collection "True Speed". They are quite heavily advertising the dirty state performance of their SSDs, although I have to say that I haven't found their SSDs to be anything special in this regard. As we already found out in the performance consistency test, Plextor relies heavily on idle garbage collection: When the drive has no other tasks to complete, it will start cleaning up itself. 

For starters, I ran a secure erased M5M through HD Tach to get the baseline performance:

As usual, I followed up by filling the drive with sequential data and then hammered the drive with 4KB random writes (QD=32) across all user-accessible LBAs for 60 minutes. I then ran HD Tach to graph the data:

Performance does get pretty bad, but that was expected given the performance consistency (the lower the random write speed is after torture, the worse the HD Tach graph looks). Next I TRIM'ed all user-accessible LBAs and reran HD Tach to make sure TRIM work as it should:

And it does.

AnandTech Storage Bench 2011 - Light Workload Power Consumption
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  • kmmatney - Wednesday, April 17, 2013 - link

    " I strongly recommend having at least 25% free space with the M5M. The more you fill the drive, the more likely it is that you'll face inconsistent performance."

    Would this really effect the average user? Do you let the drives idle long enough so the normal garbage collection can kick in?
    Reply
  • msahni - Wednesday, April 17, 2013 - link

    Hi there,
    First of all Kristian thanks for the reviews. You've finally answered my queries about the best mSATA SSD to get. (from the Intel 525 review)

    Could you please advise what is the best method to leave the 25% free space on the drive for over provisioning to enhance the performance.

    Cheers....
    Reply
  • Minion4Hire - Wednesday, April 17, 2013 - link

    Anand answered that in another article. I believe you are supposed to shrink the partition, create a second partition out of the unallocated space, then delete the new partition. The act of deleting the partition brings the OS to TRIM that portion of the drive freeing it up for use as spare area. And since you won't be writing to it any more it is permanently spare area (well, unless you repartition or something) Reply
  • xdrol - Wednesday, April 17, 2013 - link

    Actually, Windows does not trim when you delete a partition, rather when you create a new one. Reply
  • Hrel - Wednesday, April 17, 2013 - link

    I have wondered for a long time if the extra free space is really necessary. Home users aren't benchmarking, drives are mostly idle. Not often do you transfer 100GB at a time or install programs. Reply
  • JellyRoll - Wednesday, April 17, 2013 - link

    Unrealistic workloads for a consumer environment result in unrealistic test results. How many consumer notebooks or laptops, hell even enterprise mobile devices, will be subjected to this type of load? Answer: Zero.
    Even in a consumer desktop this is NEVER going to happen.
    Reply
  • JPForums - Thursday, April 18, 2013 - link

    It was stated a long time ago at Anandtech that their testing was harsher than typical consumer loads for the express purpose of separating the field. Under typical consumer workloads, there is practically no difference between modern drives. I don't know how many times I've read that any SSD is a significant step up from an HDD. It has pretty much been a standing assumption since the old jMicron controllers left the market. However, more information is required for those that need (or think they need) the performance to handle heavier workloads.

    Personally, everything else being equal, I'd rather have the drive that performs better/more consistently, even if it is only in workloads I never see. I don't think Kristian is trying to pull the wool over your eyes. He simply gives the readers here enough credit to make up their own mind about the level of performance they need.
    Reply
  • Kristian Vättö - Wednesday, April 17, 2013 - link

    If the drive is nearly full and there's no extra OP, then it's possible that even normal (but slightly larger/heavier, like app installation) usage will cause the performance to become inconsistent which will affect the overall performance (average IOPS will go down). Performance will of course recover with idle time but the hit in performance has already been experienced. Reply
  • JellyRoll - Wednesday, April 17, 2013 - link

    Running a simple trace of an application install will show that this is not an accurate statement. This testing also does not benefit from TRIM because there is no filesystem during the test. This ends up making an overly-negative portrayal. Reply
  • JPForums - Thursday, April 18, 2013 - link

    Which test in particular are you referring to that has no access to TRIM, that otherwise would?

    As far as application traces go, I can confirm Kristian's statement is accurate on both a Corsair Force GT 120GB and a Crucial M4 128GB. Performance drops appreciably when installing programs with a large number of small files (or copying a large number of small files I.E. Libraries). As an aside, it can also tank the performance of Xilinx ISE, which is typically limited by memory bandwidth and single threaded CPU performance.
    Reply

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