Orders of magnitude, in charts
Our benchmarks include a mix of real-world and synthetic testing. We normally run each test multiple times, though we admit that on the HDD we just took the results of a single run for the lengthier tests. Here are the results, with the HDD highlighted in all the charts.
The AS SSD Sequential testing gives us the best-case pure transfer performance. This is as good as it gets for both hard drives and solid state drives. Note also that the hard drive (and SSDs) is basically empty at the time of testing; if it were full of fragmented files, performance on the HDD could be substantially lower. The same is only partially true for SSDs; some can get in a degraded performance state after lots of use, but TRIM and other features will keep a modern SSD much closer to “like new” performance. (Note that the SSDs have at least had a full drive’s worth of writes, however, so we’re not showing absolute best-case SSD performance.)
If you look at the sequential transfer rates, hard drives don’t look so bad. Sure, a slow SSD is typically twice as fast, but you could live with that, right? Meanwhile, a modern NVMe drive boasts a 10X performance increase, but we’re talking about a $90 3TB HDD vs. a $1050 1.2TB SSD—$0.03 per GB vs. $0.87 per GB means it’s also 30X as expensive. Interestingly, the Intel SSD 750 “only” costs 3X as much per GB as the OCZ Trion 100 and other inexpensive SSDs, so if you do lots of sequential transfers you don’t even get diminishing returns. It’s also worth pointing out that write performance on the Trion 100 tends to start high, at over 350MB/s, but over the length of the test sequence the transfer rate steadily declines. For bursty workloads, the Trion actually fares much better; it’s just sustained writes where it starts to struggle.
Moving over to AS SSD’s Random testing, suddenly the problem with HDDs becomes strikingly obvious. The slowest SSD in our charts is over 40x as fast as the HDD in read performance, and over 60x faster in write performance… and that’s at a queue depth of one. SSDs shine when they have more stuff going on, and at QD64 the SSDs are 250x to 1,150x (that’s over three orders of magnitude!) faster at reads, and 125x to 1,150x faster at writes. Suddenly, that 30x advantage in price per GB that the HDD holds doesn’t look quite so compelling, does it?
We use IOmeter as a second test of theoretical read/write performance for sequential and random workloads, the difference being that we mix the reads and writes and take the geometric mean of the five mixes. The mixing of reads and writes has a clear impact on all the drives, though it’s most pronounced on the HDD and less on the SSDs. Sequential read/write speeds are pretty similar to the pure write speeds shown in AS SSD on several of the drives, though the OCZ Trion and Intel SSD 750 both perform better in the IOmeter write testing.
The mixed random read/write, on the other hand, continues to separate the contenders from the pretenders, and the HDD can only look on in wonder. If you’re still running a hard drive for your OS, this is a great illustration of why a system with an SSD can boot the OS in under 15 seconds, while you might end up waiting several minutes for a hard drive to become fully ready for use. Windows will load all sorts of drivers and kernel files, and the access pattern ends up looking more random than sequential in many cases. The differences become a bit less pronounced once things settle down—assuming that you have sufficient system RAM, of course—but even mediocre SSDs will easily beat the fastest HDDs.
We’ve covered mostly theoretical testing so far, but what does this mean in the “real world”? We’ll start with a file copy test, creating a clone of just shy of 20GB of data (the contents of our Steam Batman: Arkham Origins folder). This provides a split workload of 50/50 reads/writes, though the use of PowerShell tends to deliver results closer to sequential performance than random IO. (Interestingly, doing the file copy within Windows Explorer tends to be about 10–15 percent slower than using PowerShell.) We’re back to the slower SSDs only being twice as fast as a clean hard drive, while the fastest NVMe drives are nearly an order of magnitude faster; a moderately fragmented HDD would only make matters worse.
Last up is PCMark 8’s Storage test. The overall score shows less than a 2x difference between HDDs and SSDs, which makes sense: Over the course of a day using your computer, having an SSD won’t usually make you twice as efficient. Certain tasks will go much faster with the SSD, but for office work, most of the time the PC is waiting on you—with or without an SSD. In contrast, the Bandwidth result focuses on the times when you’re waiting on the computer, specifically when you’re waiting for storage. It illustrates why systems with SSDs feel so much faster: Those times where you’re waiting impatiently for the PC to boot your OS or load an application are what you notice the most.