Samsung SSD 840 EVO Review: 120GB, 250GB, 500GB, 750GB & 1TB Models Tested
by Anand Lal Shimpi on July 25, 2013 1:53 PM EST- Posted in
- Storage
- SSDs
- Samsung
- TLC
- Samsung SSD 840
Random Read/Write Speed
The four corners of SSD performance are as follows: random read, random write, sequential read and sequential write speed. Random accesses are generally small in size, while sequential accesses tend to be larger and thus we have the four Iometer tests we use in all of our reviews.
Our first test writes 4KB in a completely random pattern over an 8GB space of the drive to simulate the sort of random access that you'd see on an OS drive (even this is more stressful than a normal desktop user would see). I perform three concurrent IOs and run the test for 3 minutes. The results reported are in average MB/s over the entire time. We use both standard pseudo randomly generated data for each write as well as fully random data to show you both the maximum and minimum performance offered by SandForce based drives in these tests. The average performance of SF drives will likely be somewhere in between the two values for each drive you see in the graphs. For an understanding of why this matters, read our original SandForce article.
Random read speed is very close to that of the 840 Pro. The EVO doesn't look like a mainstream drive here at all.
Even peak random write performance is dangerously close to the 840 Pro. Only the 120GB drive shows up behind the pack. I should add that I'll have to redo the way we test 4KB random writes given how optimized current firmwares/architectures have become. The data here is interesting but honestly the performance consistency data from earlier is a better look at what happens to 4KB random write performance over time.
The relatively small difference between QD3 and QD32 random write performance shows you just how good of a job Samsung's controller is doing at write combining. At high queue depths the EVO is just as fast as the 840 Pro here. So much for TLC being slow.
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.
Sequential read and write performance, even at low queue depths is very good on the EVO. You may notice lower M500 numbers here than elsewhere, the explanation is pretty simple. We run all of our read tests after valid data has been written to the drive. Unfortunately the M500 attempts to aggressively GC data on the drive, so even though we fill the drive and then immediately start reading back the M500 is already working in the background which reduces overall performance here.
AS-SSD Incompressible Sequential Read/Write 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.
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halbhh2 - Saturday, July 27, 2013 - link
Exactly. I found that even moving up from 8GB to 16GB had a great effect for me with an old Samsung F3 hard drive. The difference: after just 30 minutes from boot, loading an often used program like iTunes (for podcasts) was very similar to the speed on my laptop which has an 830 SSD and only 4GB. Both load in about 4 seconds, and the 16GB desktop loads so fast because it has had time to cache a lot of iTunes. Before the ram upgrade, that load time for iTunes on the desktop computer was about 14 seconds. Quite a difference due to windows 7 caching. The extra improvement I'd get from installing an SSD onto the desktop computer now would be modest, since I usually only need to reboot once or twice in a week. Still, the sweet spot of price/performance for me is approaching, probably around $60-$70, and that won't be long.Klimax - Sunday, July 28, 2013 - link
It's in wrong place. Unlike OS level caching (at least in Windows), which is in cooperation between memory manager, cache manager and file system driver, this is too low in the chain and sees only requests but nothing else and also takes memory from OS and takes too few.Coup27 - Thursday, July 25, 2013 - link
Typo: "although I wouldn't recommend deploying the EVO in a write heavy serve Microsoft's eDrive standard isn't supported at launch"Excellent article. Samsung continue to push SSDs and I'm really excited about RAPID. Is the 840 Pro due for a successor any time soon? I am selling my current ATX Sandy Bridge + 830 and getting a mITX Haswell + (840 Pro?) and want the fastest Samsung consumer SSD available and I'd be gutted to buy an 840 Pro to see it's successor released a few weeks later.
vLsL2VnDmWjoTByaVLxb - Thursday, July 25, 2013 - link
Another typo last page:"Even though its performnace wasn't class leading, it was honestly good enough to make the recommendation a no-brainer. "
JDG1980 - Thursday, July 25, 2013 - link
Will there be an 840 EVO Pro coming out later? To me, TLC is still a deal-breaker.By the way, what happens if power goes out during a TurboWrite (before the data has been written to the normal storage space)? Does this result in data loss, or, worse, bricking? I'd suspect Samsung at least avoided the latter, but I'd like to see some confirmation on this.
sherlockwing - Thursday, July 25, 2013 - link
I guess you didn't read the Endurance part of the review? Even if you write 100GiB a day all of those drives last longer than their warranty( 3 years), that's more than enough endurance.Coup27 - Thursday, July 25, 2013 - link
Some people just don't want to accept the facts. TLC could get to 99.9% of MLC endurance and people would still want MLC. I've been deploying 840's in a light duty enterprise environment and they've been fine. The only reason I use MLC at home is because I want the absolute fastest performance and I can afford it, not that I actually need it.Oxford Guy - Thursday, July 25, 2013 - link
The SanDisk Extreme 240 was just on sale for $150. TLC NAND still seems like a solution in need of a problem.Spunjji - Friday, July 26, 2013 - link
You can approach TLC pricing with an MLC drive in a sale, but the fact remains that when it comes to actual sustainable production pricing TLC NAND has a 50% density (and thus manufacturing cost advantage) over MLC. Given that NAND price determines drive cost and drive costs are the primary barrier of entry to SSDs, I'm fairly sure it has a problem to solve.FWIW I have not seen any drive touch the 120GB 840's price here in the UK, on sale or otherwise.
Oxford Guy - Friday, July 26, 2013 - link
However, there is also the problem of increasing latency and lifespan from node shrinkage.