Thursday, August 29th 2024
Disabled SLC Cache Tested on M.2 SSD, Helps Performance in Some Cases
Gabriel Ferraz, maintainer of the TechPowerUp SSD database and content creator, recently published an article that shows the relationship between SLC (Single-Level Cell) cache technology and its performance impact on SSDs. Using a Pichau Aldrin Pro 2 TB SSD featuring an Innogrit IG5236 controller and YMTC 128-layer TLC NAND, Gabriel has uncovered both the advantages and potential drawbacks of this feature. The article reveals that with SLC cache enabled, which acts as a high-speed buffer, the SSD achieved remarkable write speeds of up to 6.5 GB/s, but only until 691 GB had been written. Beyond that, speeds dropped to 2.2 GB/s and then to 860 MB/s as the drive filled up.
Disabling the SLC cache delivers more consistent performance results that are 2.1 GB/s across the whole capacity of the SSD, but with lower peak performance. Testing also examined the impact on power consumption and efficiency. With the SLC cache active, the SSD consumed approximately 5 W of power while achieving over 3000 MB/s bandwidth. Disabling the cache reduced power consumption but at the cost of halving the bandwidth to around 1900 MB/s, resulting in lower overall efficiency. Maximum power consumption with cache enabled peaked at 7.3 W, compared to a lower figure when operating in constant TLC mode. Below, you can see some performance benchmarks published on The Overclock Page.
Interestingly, in real-world scenarios such as game loading times and Windows boot speeds, the difference between cached and non-cached performance was minimal. Synthetic game benchmarks and Windows boot tests showed negligible variations, suggesting that current software may not be fully optimized to leverage the speed offered by SLC cache, likely due to the prevalence of random 4K operations demanded by software, which NAND flash is not optimal for, rather being ideal for sequential operations. File transfer tests, however, tell a different story. Copying large files and game installations took more than twice as long with the cache disabled, highlighting the significant advantage of SLC cache in data-intensive sequential tasks.
For complete benchmarks and in-depth explanation, check out the original article by Gabriel.
Source:
The Overclock Page
Disabling the SLC cache delivers more consistent performance results that are 2.1 GB/s across the whole capacity of the SSD, but with lower peak performance. Testing also examined the impact on power consumption and efficiency. With the SLC cache active, the SSD consumed approximately 5 W of power while achieving over 3000 MB/s bandwidth. Disabling the cache reduced power consumption but at the cost of halving the bandwidth to around 1900 MB/s, resulting in lower overall efficiency. Maximum power consumption with cache enabled peaked at 7.3 W, compared to a lower figure when operating in constant TLC mode. Below, you can see some performance benchmarks published on The Overclock Page.
44 Comments on Disabled SLC Cache Tested on M.2 SSD, Helps Performance in Some Cases
Anyway, I've seen occasional reports that SLC cache becomes ineffective when the SSD is close to full. I tend to blame internal fragmentation for that, as SLC caching probably needs large extents of contiguous free space, so it can write large chunks of data sequentially (random/fragmented would be slow).If I'm allowed to make a suggestion, here it is: please record the SMART data and report how much data each of your benchmarks writes to the SSD. As far as I'm aware, no SSD reviewer does that. OS booting and game loading probably write little data, but it would be nice to have a proof. That would be the reason why disabling the SLC cache has little effect.
Please transfer data responsibly. :D
(for those outside americas, check Dos Equis commercials on yt)
For all my drives e.g. the likely biggest sustained write is when/if I am migrating data from a drive it is replacing, a one off event.
After I got my SN850X I did move a couple of hundred gigs worth of games of my 980 pro though. But I wont be doing this sort of thing often. Plus it wasnt all in one go, one game at a time, with gaps in between.Probably the worst time to get rid, pSLC also increases endurance, and you want that if the drive is nearly full.
The NAND is the same. There might be some binning, but it's the same NAND.
Price difference mainly comes from Controller/Firmware/Support you're paying for the RnD.
It would actually make more sense from a supply chain/cost perspective to have just 1 "type" of NAND.
I'm aware I'm making an enterprise-to-enterprise comparison instead of enterprise-to-consumer but still. There must be a significant price difference due to the NAND.
www.techpowerup.com/ssd-specs/intel-670p-1-tb.d431
www.techpowerup.com/ssd-specs/solidigm-d7-p5510-7-5-tb.d1331
shame there's no info here for the P5316
Enterprise drives also employ eMLC, eTLC, eQLC. This may mean different things to different manufacturers but, as Intel explained in the MLC era, it's made up of three components: binned NAND, more overprovisioned space, and slower writing. Slower writing is more accurate and can push lower voltages to storage cells when writing and erasing. The voltages for erasing are higher than those for writing, that's probably how it has to be, and so I assume that erasing contributes most to NAND wear.
So that "some" binning is actually not something to overlook, and may increase the (market) value of a NAND die considerably.