Samsung SSD 845DC EVO/PRO Performance Preview & Exploring IOPS Consistency
by Kristian Vättö on September 3, 2014 8:00 AM ESTInitial Thoughts
Since we are dealing with two drives, it makes sense to split the conclusion into two and I will start with the 845DC PRO. While all we have today is a performance preview, the 845DC PRO is turning out to be one of the best enterprise SATA SSDs that we have tested. With only 28% over-provisioning, the PRO offers the most consistent 4KB random write performance that we have seen to date. When you add the fact that the PRO is also rated at ten drive writes per day, it is shaping up to be an excellent drive for write intensive workloads.
| Price Comparison - MSRP | |||||||||
| Capacity | 400GB | 800GB | |||||||
| Samsung 845DC PRO | $960 ($2.4/GB) | $1,830 ($2.29/GB) | |||||||
| Intel SSD DC S3700 | $729 ($1.82/GB) | $1,459 ($1.82/GB) | |||||||
While the performance is great, pricing could be more competitive. Intel's DC S3700 is considerably cheaper at both capacities and offers the same 10 drive writes per day endurance. The 845DC PRO does provide higher 4KB random write performance (~50K IOPS vs ~35K IOPS) and is a bit more consistent, but ultimately the workload determines whether the extra performance is worth the extra cost. For workloads where absolute performance is more important than capacity, the 845DC PRO is a better pick as it provides slightly more IOPS per dollar, but the S3700 still offers lower $/GB if capacity is a concern. Of course, as enterprise SSDs are usually bought in bulk, the prices may vary depending on the volume and the MSRPs listed here may not be fully accurate.
| Price Comparison - MSRP | |||||||||
| Capacity | 240GB | 480GB | 800/960GB | ||||||
| Samsung 845DC EVO | $250 ($1.04/GB) | $490 ($1.02/GB) | $969 ($1.01/GB) | ||||||
| Intel SSD DC S3500 | $219 ($0.91/GB) | $439 ($0.91/GB) | $729 ($0.91/GB) | ||||||
While the 845DC EVO is not crafted for write-intensive workloads, it still provides very consistent random write performance, although obviously the performance is lower than the PRO's. The EVO is very comparable to Intel's SSD DC S3500 as both have random write IOPS of around 15K and even the consistencies are close to a match. Endurance wise both are rated at about 0.35 drive writes per day despite the fact that Samsung is using TLC NAND instead of MLC, so it is clear that Samsung is going directly after Intel's S3500 with the EVO. It is too early to make any final conclusions yet as the EVO is really designed for mixed and read-centric workloads, which are not included in our performance preview, but if the write performance consistency is any clue the EVO will be a tough competitor for Intel's S3500.
Unfortunately I do not have an ETA for the full review yet. It will be a while, though, because testing an enterprise SSD takes a long time as the drive must be tested in steady-state to mimic a realistic scenario, and I need to test a bunch of older drives to have more data points. Moreover, there are some very interesting client drives coming in the next few weeks that will take priority, but the full review is coming along with our new enterprise SSD test suite. Today is a glimpse of some of the new things that we will be looking at, but the full suite will be way more extensive than what you have seen today. Stay tuned!
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hojnikb - Wednesday, September 3, 2014 - link
Looks like, they ain't doing Turbowrite on TLC models :)Kristian Vättö - Wednesday, September 3, 2014 - link
TurboWrite wouldn't make any sense on an enterprise drive because all that matters is sustained performance. Client drives are a different case because IO activity tends to happen in bursts, so having a fast buffer is beneficial (and it makes the drive look better in benchmarks).hojnikb - Wednesday, September 3, 2014 - link
Yeah i figured as much. Aside from being more suited for short bursts (as you'd said) its really great for marketing department, since they can slap magical 500MB/s+ speeds, that every uninformed buyer is after. 500MB/s sure sells a lot better than 250MB/s (or even less, if we're dealing with lower capacities) :)Spirall - Wednesday, September 3, 2014 - link
Thanks for the article. Would suggest to make a $/manufacturer declared write endurance comparison (PB writen until manufacturer write warranty end). If there's a chance (due to the difficult on testing time) also make a $/tested write life (PB writen until tested dead).Kristian Vättö - Wednesday, September 3, 2014 - link
$/endurance is certainly something I will be looking at in the future. This was more of a preview than a full review and in the full review I will have more graphs and comparisons to support the conclusions :)As for actual endurance testing, that is something I will not do. It took me two weeks of continuos writing to get the rated endurance to drop by 1% in the 845DC PRO, so it would take way too long to wait for the drive to die.
hojnikb - Wednesday, September 3, 2014 - link
And there is a good chance, that thing would still go strong after rated endurance would drop to 0% (unless its hardcapped to die after that).Essence_of_War - Wednesday, September 3, 2014 - link
Another excellent article, Kristian.A question/comment, though, do you think it would make more sense to report the stdev measurements as an "error bar" attached to each data point rather than an additional graph with a 2nd y-axis? I think that might be more compact without having to worry about having multiple y-scales to read. Then it might even be possible to plot an average + error bars data set for multiple different SSDs on the same axis w/o having to worry about which curve is the avg, which curve is the stdev, etc.
hulu - Wednesday, September 3, 2014 - link
Another way to present the standard deviation data would be to draw it in two average +/- stdev graphs above and below the average graph. This would better allow visualizing the actual values the average minus stdev has.Kristian Vättö - Thursday, September 4, 2014 - link
Thanks for the suggestion. I will certainly look into alternative ways to present the standard deviation. I need to redo the graphs anyway for our new suite, so while I'm at it I can see if there is a better way to present the data.Essence_of_War - Thursday, September 4, 2014 - link
Best luck then, I'm sure you'll figure out a good way to do it.