Head To Head: Crucial's M500s Vs. Samsung's 840 EVOs
The M500s And 840 EVOs Mix It Up
Samsung recently sent us four different capacities of its 840 EVO. As it turns out, we also have four Crucial M500s, one of which came to us from our German team, one that was sampled by Crucial, and two we bought online. Naturally, we wanted to know how they match up against each other.
These drives aren't always going to fit the same applications, but they clearly have more than a few attributes in common, despite their dissimilarities. The M500s are built using 128 Gb, two-bit-per-cell MLC, feature RAIN redundancy, and power loss protection. The 840 EVO does its work with three-bit-per-cell flash, emulated SLC caching, and, well, that's it, mostly.
Samsung's new offerings don't offer the same TCG Opal 2.0 and eDrive security...at least not yet. With eDrive, cryptographic functions are hardware-accelerated, and Microsoft's built-into-Windows BitLocker can exploit it in Windows 8. That's going to get added to the 840 EVO in an upcoming firmware release. In contrast, the M500 is loaded with security features. I made the mistake of referring to the M500's security and encryption as just "fairly high-end," and was quickly interrupted by Micron representatives, who pointed out that, at the time, it had the highest-end suite of security features available. That's a fair point, and true as of this moment, though probably not for long.
So how about a few direct performance comparisons?
M500 Vs. 840 EVO : Sequential Read And Write
This is a chart housing four other charts, showing sequential read scaling versus sequential write scaling. The first graph pits the 120 GB M500 against Samsung's 120 GB 840 EVO, and so on. The M500s are shown in blue, and the 840 EVOs are purple.
Samsung enjoys an advantage over the M500s. At every capacity, read and write performance belongs to the 840 EVO. As far as reads go, specifically, the M500s start off a bit slower and don't ramp up to the 840's speed until we use a queue depth of four. This could be an artifact of the way Iometer's tests are performed, but there's a 200 MB/s gap between the drives at a queue depth of one.
The writes are more complicated. Samsung employs its Turbo Write emulated SLC caching scheme to improve performance. At first, we push too much data into the buffer to achieve optimal performance on the 840 EVOs, so the write numbers aren't what they should be. Without that cache, the EVOs are no faster than Samsung's original 840 (in other words, equal to or slower than the M500). But you won't see that here.
The situation gets even stickier when we test with random 4 KB blocks.
M500 Vs. 840 EVO : Random Read And Write
At a queue depth of one, both vendors nail high 4 KB results. The 840 EVO enjoys an edge as the three larger capacities break 10,000 IOPS. The M500s hold their own, though they lose out to the current random read champion at a queue depth of one. From there, though the gap narrows, the 840 EVOs maintain their lead, even at higher queue depths.
Random writes play out a bit differently. The 120 GB 840 EVO chokes early, dropping down into scandalously-low numbers at a queue depth of one. Otherwise, we essentially get a wash from the three larger-capacity SSDs in each family.