Random Read Performance

One of the major changes in our 2015 test suite is the synthetic Iometer tests we run. In the past we used to test just one or two queue depths, but real world workloads always contain a mix of different queue depths as shown by our Storage Bench traces. To get the full scope in performance, I'm now testing various queue depths starting from one and going all the way to up to 32. I'm not testing every single queue depth, but merely how the throughput scales with the queue depth. I'm using exponential scaling, meaning that the tested queue depths increase in powers of two (i.e. 1, 2, 4, 8...). 

Read tests are conducted on a full drive because that is the only way to ensure that the results are valid (testing with an empty drive can substantially inflate the results and in reality the data you are reading is always valid rather than full of zeros). Each queue depth is tested for three minutes and there is no idle time between the tests. 

I'm also reporting two metrics now. For the bar graph, I've taken the average of QD1, QD2 and QD4 data rates, which are the most relevant queue depths for client workloads. This allows for easy and quick comparison between drives. In addition to the bar graph, I'm including a line graph, which shows the performance scaling across all queue depths. To keep the line graphs readable, each drive has its own graph, which can be selected from the drop-down menu.

I'm also plotting power for SATA drives and will be doing the same for PCIe drives as soon as I have the system set up properly. Our datalogging multimeter logs power consumption every second, so I report the average for every queue depth to see how the power scales with the queue depth and performance.

Iometer - 4KB Random Read

Random read performance at small queue depths has never been an area where the Vector 180 has excelled in. Given that these are one of the most common IOs, it's an area where I would like to see improvement on OCZ's behalf.

Iometer - 4KB Random Read (Power)

Power consumption, on the other hand, is excellent, which is partially explained by the lower performance. 

Samsung SM951 512GB

Having a closer look at the performance data across all queue depths reveals the reason for Vector 180's poor random read performance. For some reason, the performance only starts to scale properly after queue depth of 4, but even then the scaling isn't as aggressive as on some other drives. 

Random Write Performance

Write performance is tested in the same way as read performance, except that the drive is in a secure erased state and the LBA span is limited to 16GB. We already test performance consistency separately, so a secure erased drive and limited LBA span ensures that the results here represent peak performance rather than sustained performance.

Iometer - 4KB Random Write

In random write performance the Vector 180 does considerably better, although it's still not the fastest drive around. 

Iometer - 4KB Random Write (Power)

Even though the random write performance doesn't scale at all with capacity, the power consumption does. Still, the Vector 180 is quite power efficient compared to other drives.

Samsung SM951 512GB

The Vector 180 scales smoothly across all queue depths, but it could scale a bit more aggressively because especially the QD4 score is a bit low. On a positive side, the Vector 180 does very well at QD1, though.

AnandTech Storage Bench - Light Sequential Performance
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  • Guspaz - Tuesday, March 24, 2015 - link

    Well, one person in particular had difficulty remembering the proper saying while in Tennessee... Reply
  • Minion4Hire - Tuesday, March 24, 2015 - link

    He's quoting George Bush. Reply
  • mapesdhs - Wednesday, March 25, 2015 - link

    And hence not exactly a viable rationale for concluding anything about anything.

    Ian.
    Reply
  • CaedenV - Tuesday, March 24, 2015 - link

    Cant beat the Evo on price, performance, or support... so then what is the point? Reply
  • kmmatney - Tuesday, March 24, 2015 - link

    None of the benchmarks include the EVO, so it's hard to tell if it beats it or not. It is probably faster, but the MSRP is the same as the 850 Pro, which definitely beats it in most tests. Reply
  • ocztosh - Tuesday, March 24, 2015 - link

    Hi CaedenV, thank you for your feedback. The Vector 180 is designed for the high performance/workstation market and is not positioned versus the TLC based EVO. When it comes to best balance of performance/value our ARC series (based on MLC). We will be coming out with future products that push the value envelope that leverage Toshiba TLC. Reply
  • mapesdhs - Wednesday, March 25, 2015 - link

    I was impressed with the Arc 100, it was quicker than I expected. Any data yet on return
    rates? It would be interesting to know if it's been competitive with the 850 EVO in that regard.
    Samsung has a strong reputation here. My main concern with the Vector 180 though is it will
    appear too expensive compared to the 850 Pro and SanDisk Extreme Pro.

    Ian.
    Reply
  • chrnochime - Tuesday, March 24, 2015 - link

    The point is some ppl don't actually want to use TLC. Reply
  • ocztosh - Wednesday, March 25, 2015 - link

    Hi chrnochime, thank you for your comments. We so agree there are still a lot of customers that would still prefer MLC. Our current value drive series is MLC based and even after we introduce a TLC based Series we will continue to deliver MLC drives for those customers that are looking for drives higher up the performance spectrum. Reply
  • chrnochime - Tuesday, March 24, 2015 - link

    Support? So how long did that TLC fix take to be available again? Reply

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