Sequential Read/Write Speed

To measure sequential performance I ran a 3 minute long 128KB sequential test over the entire span of the drive at a queue depth of 1. The results reported are in average MB/s over the entire test length.

Iometer - 128KB Sequential Write

This is pretty impressive. The new SF-2500 can write incompressible data sequentially at around the speed the SF-1200 could write highly compressible data. In other words, the Vertex 3 Pro at its slowest is as fast as the Vertex 2 is at its fastest. And that's just at 3Gbps.

The Vertex 3 Pro really shines when paired with a 6Gbps controller. At low queue depths you're looking at 381MB/s writes, from a single drive, with highly compressible data. Write incompressible data and you've still got the fastest SSD on the planet.

Micron is aiming for 260MB/s writes for the C400, which is independent of data type. If Micron can manage 260MB/s in sequential writes that will only give it a minor advantage over the worst case performance of the Vertex 3 Pro, and put it at a significant disadvantage compared to OCZ's best case.

Initially, SandForce appears to have significantly improved performance handling in the worst case of incompressible writes. While the old SF-1200 could only deliver 63% of its maximum performance when dealing with incompressible data, the SF-2500 holds on to 92% of it over a 3Gbps SATA interface. Remove the SATA bottleneck however and the performance difference returns to what we're used to. Over 6Gbps SATA the SF-2500 manages 63% of maximum performance if it's writing incompressible data.

Note that the peak 6Gbps sequential write figures jump up to around 500MB/s if you hit the drive with a heavier workload, which we'll see a bit later.

Iometer - 128KB Sequential Read

Sequential read performance continues to be dominated by OCZ and SandForce. Over a 3Gbps interface SandForce improved performance by 20 - 40%, but over a 6Gbps interface the jump is just huge. For incompressible data we're talking about nearly 400MB/s from a single drive. I don't believe you'd even be able to generate the workloads necessary to saturate a RAID-0 of two of these drives on a desktop system.

 

Random Read/Write Speed The Performance Degradation Problem
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  • jwilliams4200 - Friday, February 18, 2011 - link

    In that case, it would be helpful to print two after-TRIM benchmarks: (1) immediately after TRIM and (2) steady-state after-TRIM (i.e., TRIM, let the drive sit idle for long enough for GC to complete, then benchmark again) Reply
  • jcompagner - Thursday, February 17, 2011 - link

    what i never understood or maybe i should read a bit more the previous articles, is that how come that a SSD can write many times faster then it can read?
    It seems to me that read is way easier to do then write...
    Reply
  • vol7ron - Friday, February 18, 2011 - link

    I originally thought that, but SSDs first write to the controller, which organizes the data for storing it to the disk. The major point is that the data can go anywhere in the array of NAND nodes and the list of the next available node in the stack is available almost immediately, whereas a read requires a hash lookup of where the data is stored, which means the seek could take longer to accomplish.

    I, as well, am not certain that's true, but that's my best guess.
    Reply
  • AnnihilatorX - Saturday, February 19, 2011 - link

    Only for Sandforce controllers.
    Sandforce compresses the incoming data at real time. If the incoming data is highly compressible, in a very extreme example, writting a 500MB blank text file, will be instantaneous. So you see 500MB/ms or something ridiculous.

    It is also possible for write speeds to exceed read in burst when small amount of data is written to DRAM on other controllers
    Reply
  • Soul_Master - Thursday, February 17, 2011 - link

    For zero impact from source performance, I suggest to copy data from RAM drive to your test hard disk. Reply
  • Anand Lal Shimpi - Thursday, February 17, 2011 - link

    That's a great suggestion. I ran out of time before I left the country but I'll be playing with it some more upon my return :)

    Take care,
    Anand
    Reply
  • MrBrownSound - Thursday, February 17, 2011 - link

    I think the intel x25m was a pretty good control group to send the data from. I would auctally like to see the changes when sending the data through the RAM; that would be interesting. Reply
  • Hacp - Thursday, February 17, 2011 - link

    Anand,
    You still direct your readers to your Vertex2 article but OCZ has changed its performance on those drives. Your results are no longer valid and it would be dishonest to link the old Vertex2 performance numbers in this new article when they do not reflect the new slower performance of the Vertex2 today.
    Reply
  • Anand Lal Shimpi - Thursday, February 17, 2011 - link

    I've seen the discussion and based on what I've seen it sounds like very poor decision making on OCZ's behalf. Unfortunately my 25nm drive didn't arrive before I left for MWC. I hope to have it by the time I get back next week and I'll run through the gamut of tests, updating as necessary. I also plan on speaking with OCZ about this. Let me get back to the office and I'll begin working on it :)

    As far as old Vertex 2 numbers go, I didn't actually use a Vertex 2 here (I don't believe any older numbers snuck in here). The Corsair Force F120 is the SF-1200 representative of choice in this test.

    Take care,
    Anand
    Reply
  • Quindor - Thursday, February 17, 2011 - link

    Good to hear that you are addressing the problems surrounding the Vertex 2 drives. There aren't many websites out there which deliver well thought through reviews and bechmarks such as Anandtech does, although some are getting better.

    I did some benchmarks on my own and with the new 25nm NAND the new 180GB OCZ Vertex2 can actually be slower then my more then a year old 120GB OCZ Vertex1.

    If anyone is interested. They can find an overview of the benchmarks performed on the following page. https://picasaweb.google.com/quindor/Benchmarks#

    Still, I would love to see an in depth comparsion as you are famous for. ;)

    For my personal usage scenario (my own ESXi server), the speed decrease will be of minimal effect because running multiple template cloned guests, the dedup and compression should be able to do their work just fine. ;)
    Reply

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