Following up the impressive MX500 Crucial sent in it’s smaller sibling the BX500 for review. Unlike other reviews we have the privilege of being sent both the 480GB and 960GB versions allowing a better look at how performance scales. Furthermore the BX500 represents our first look at an SSD with no dram cache.
Our Test system and Procedure
As always we have our standard test system based on an i5-7600K. The system is running windows 10 Professional and was under no load(AV disabled) for all tests. Testing will consist our standard set of tests which we outlined previously.
Packaging is what we’ve come to expect with Crucial. We have a retail friendly package clearly indicating the drive model and capacity. Crucial still includes it’s typical shim as well. I do find the packaging a bit lacking in that it doesn’t call attention to the lack of a dram cache something consumers might want to know without digging into the spec sheets. Unfortunately we don’t have the ability to non destructively open the BX500 thanks to the use of a plastic snapped together shell, this is disappointing but understandable in a cost optimized device.
|NAND||Micron 2nd Gen 256Gbit 3d TLC||Micron 2nd Gen 256Gbit 3d TLC||Micron 2nd Gen 256Gbit 3d TLC||Micron 2nd Gen 256Gbit 3d TLC|
|Sequential Read||560 MB/s||560 MB/s||560 MB/s||560 MB/s|
|Sequential Write||510 MB/s||510 MB/s||510 MB/s||510 MB/s|
|4k Random Read||95,000 IOPS||95,000 IOPS||95,000 IOPS||95,000 IOPS|
|4k Random Write||90,000 IOPS||90,000 IOPS||90,000 IOPS||90,000 IOPS|
|Dimensions||7mm X 69.85mm X 100.5mm||7mm X 69.85mm X 100.5mm||7mm X 69.85mm X 100.5mm||7mm X 69.85mm X 100.5mm|
|Warranty||3 years||3 years||3 years||3 years|
What makes a Dramless drive different
Most mainstream and high end ssds ship with a dram cache with roughly 1MB of ram per 1Gb of data(so 1Gb of ram in at typical 1TB ssd). The applications for this are twofold, one is to buffer incoming writes from the host so that they can be written to NAND in a more sensible manner allowing the drive to reach higher levels, and more consistent performance. The other is the storage of(at least a portion of) the flash translation layer. This translates where your operating system thinks data is to where it actually is in NAND. These two locations tend to differ as ssd’s implement things like wear leveling transparently to the operating system. Without this external cache the BX500 will have to rely on a combination of a small amount of memory in it’s controller as well the nand directly instead.
SSD-z is still having issues with 3d nand and newer controllers, if someone has an alternative to it(or can contact http://aezay.dk/) we’re open to suggestions. What we do see is working TRIM for this drive. Although SSD-Z isn’t reporting it we know from the spec sheets that Crucial is using the SM2258XT from Silicon Motion. The SMART caution isn’t reflected in other tools and appears to be a false positive in this instance.
Atto shows a rapid ramp up for the BX500 likely thanks to an SLC caching layer. What’s more impressive is seeing both models hold at interface limits once they reach their peak. Typically we would have expected to see a drop once they ran out of cache however it appears that the SM2258XT is up to the task.
Charted against the rest of our devices seeing the BX500 not stick out is a good sign here. We aren’t seeing any sort of massive performance deficit with the controller change and even a few improvements for the better. The larger model with more space to work with seems to edge out past it’s smaller sibling although not to any significant degree. Both outperform the older BX300 which took a long time to reach peak performance a welcome generational change.
We were promised 560/510 for sequential performance and at QD32 where vendors like to test they over deliver. Even down at QD1 we aren’t far from the listed performance something we’ve seen other drives take a much bigger hit on, especially regarding writes. What we do see is the lack of a cache starting to show up, random performance on the larger drive shows a distinct drop compared to it’s smaller sibling, having more data to work with is that much harder for it.
Crystal Disk Mark manages to highlight some of the segmentation between the MX and BX series drives from crucial. Although not bad performance we’re not keeping up on random workloads this isn’t a drive you want a database application running on as we’ll see exaggerated further later.
Anvil gives us a good look at response times which appear to be as good as ever which is a welcome sight. The lack of a dram cache isn’t causing massive increases in latency in these tests keeping us at mainstream sata level performance.
With other drives as comparison points anvil really helps highlight how much of a mixed bag the BX500 can be. When it’s keeping up it does so towards the very top, even beating it’s mainstream counterpart. When it doesn’t though it’s outperformed by budget drives like the UV500 and the 1TB mushkin reactor a 5 year old design.
AS SSD helps validate some of the values we saw earlier. It also drives home that the 1Tb drive contrary to normal is really the slower of the two. Performance normally increases as working area and parallelism increases however in this instance it leads to more work for a controller that’s already resource deprived.
The BX500 isn’t really showing any surprises here. Anything with a dram cache typically has an advantage even older budget drives like it’s predecessor do better in AS SSD.
With two capacities we see suprisingly different results. The smaller drive actually performs better overall with a higher peak and a lower floor at just over 2k IOPS. The larger unit struggles to maintain 1k IOPS the extra strain on it’s controller keeping performance lower across the board.
These aren’t drives you want for a high performance database as we saw indications of earlier. The BX500 in both it’s capacities set new records for worst consistency of a modern drive(the worst before was the usb attatched SE730H at 1.58) and worst overall of everything we’ve tested at the 960gb model coming in below the Accelsior E2 which had been the bottom at .679. That doesn’t inherently make these bad drives but they certainly aren’t something you want to count on delivering consistent performance in a write heavy scenario.
We’re going to skip pricing comparisons that we would normally do thanks to the current health crisis. List pricing and availability are all over the board making any evaluations done today irrelevant by tomorrow. We will follow up with a state of the market once things settle back to a normal routine.
The BX500 manages to impress, we’ve avoided drives without a dram cache to date due to their performance pitfalls and a desire to not endorse them in any manner. However, powered by the SM2258XT and flash directly from parent company micron, crucial manages to avoid most of the flaws with the true nature of the drive only showing up in our most extreme tests. Overall I wouldn’t suggest the BX500 for anything data heavy but it would serve just fine for uses such as a steam library or being thrown in an external enclosure to move data from A to B without worrying about moving parts. Although I would prefer a more consistent drive it is better than a spinning disk if considering something for a bottom budget upgrade to an existing PC as well. With current list prices of 59.99 for the 480gb model and 99.99 for the 1Tb variant the BX500 is priced for it’s role as bulk storage although availability and pricing is in a constant state of change thanks to the current pandemic.