Sequential Read/Write Speed

To measure sequential performance I ran a 1 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.

Desktop Iometer - 128KB Sequential Read (4K Aligned)

Low queue depth sequential read performance is among the better drives, but still slightly behind Samsung.

Desktop Iometer - 128KB Sequential Write (4K Aligned)

Write performance continues to be the Vector's strong suit, here only Intel's SSD 520 with easily compressed data pulls ahead.

AS-SSD Incompressible Sequential Performance

The AS-SSD sequential benchmark uses incompressible data for all of its transfers. The result is a pretty big reduction in sequential write speed on SandForce based controllers.

Incompressible Sequential Read Performance - AS-SSD

High queue depth sequential IO shows significant clustering at the top of the charts thanks to the limits of 6Gbps SATA. The Vector pushes performance pretty much as fast as possible here.

Incompressible Sequential Write Performance - AS-SSD

Switching to writes does shake loose some of the weaker competitors, but the Vector and 840 Pro still emerge as the strongest. Corsair's Neutron GTX does very well here.

Random IO Performance Performance vs. Transfer Size
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  • kmmatney - Tuesday, November 27, 2012 - link

    I don't see anything wrong with stating that. My 256 Samsung 830 also appears as a 238GB drive in windows... Reply
  • jwilliams4200 - Tuesday, November 27, 2012 - link

    The problem is that "formatting" a drive does not change the capacity.

    Windows is displaying the capacity in GiB, not GB. It is just Windows bug that they label their units incorrectly.
    Reply
  • Gigaplex - Tuesday, November 27, 2012 - link

    Yes and no. There is some overhead in formatting which reduces usable capacity, but the GiB/GB distinction is a much larger factor in the discrepancy. Reply
  • jwilliams4200 - Wednesday, November 28, 2012 - link

    The GiB/GB bug in Windows accounts for almost all of the difference. It is not worth mentioning that partitioning usually leaves 1MiB of space at the beginning of the drive. 256GB = 238.4186GiB. If you subtract 1MiB from that, it is 238.4176GiB. So why bother to split hairs? Reply
  • Anand Lal Shimpi - Wednesday, November 28, 2012 - link

    This is correct. I changed the wording to usable vs. formatted space, I was using the two interchangeably. The GiB/GB conversion is what gives us the spare area.

    Take care,
    Anand
    Reply
  • suprem1ty - Thursday, November 29, 2012 - link

    It's not a bug. Just a different way of looking at digital capacity. Reply
  • suprem1ty - Thursday, November 29, 2012 - link

    Oh wait sorry I see what you mean now. Disregard previous post Reply
  • flyingpants1 - Wednesday, November 28, 2012 - link

    I think I might know what his problem is.

    When people see their 1TB-labelled drive displays only 931GB in Windows, they assume it's because formatting a drive with NTFS magically causes it to lose 8% of space, which is totally false. Here's a short explanation for newbie readers. A gigabyte (GB) as displayed in Windows is actually a gibibyte (GiB).

    1 gibibyte = 1073741824 bytes = 1024 mebibytes
    1 gigabyte = 1000000000 bytes = 1000 megabytes = 0.931 gibibytes
    1000 gigabytes = 931 gibibytes

    Windows says GB but actually means GiB.

    SSDs and HDDs are labelled differently in terms of space. Let's say they made a spinning hard disk with exactly 256GB (238GiB) of space. It would appear as 238GB in Windows, even after formatting. You didn't lose anything,
    because the other 18 gigs was never there in the first place.

    Now, according to Anandtech, a 256GB-labelled SSD actually *HAS* the full 256GiB (275GB) of flash memory. But you lose 8% of flash for provisioning, so you end up with around 238GiB (255GB) anyway. It displays as 238GB in Windows.

    If the SSDs really had 256GB (238GiB) of space as labelled, you'd subtract your 8% and get 235GB (219GiB) which displays as 219GB in Windows.
    Reply
  • flyingpants1 - Wednesday, November 28, 2012 - link

    IMO drive manufacturers should stop messing around and put 256GiB of USABLE space on each 256GiB drive, and start marking them as such. Reply
  • Holly - Wednesday, November 28, 2012 - link

    Tbh imho using base 10 units in binary environment is just asking for a facepalm. Everything underneath runs on 2^n anyway and this new "GB" vs "GiB" is just a commercial bullshit so storage devices can be sold with flashier stickers. Your average raid controller bios will show 1TB drive as 931GB one as well (at least few ICHxR and one server Adaptec I have access to right now all do). Reply

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