SSD's DRAM cache not showed

[Shou Miko]

I am looking around for 1TB SSD's but a lot of companies lists they are got cache like DRAM, SLC or no DRAM cache at all and it's not easy to find because most manufactores doesn't state the cache size.

But I know most of the times the price of the SSD should give a hit on if it got cache or not.

But I feel a bit like it's a taboo to actually tell if the SSD got cache or not and I don't understand why it's such a secret

I actually found a review of the Ace A55 SSD from Silicon Power that shows the cache module which is a Nanya 128MB DRAM module:

Review link: https://www.enostech.com/silicon-power-ace-a55-256gb-ssd-review/

I been looking to buy some 1TB SSD's for fast and good storage and this SSD is about £21 cheaper then the Samsung 860 Evo 1TB which got 1GB DRAM cache module but I am still left with the feeling that it's really a taboo to show the cache dram size of a ssd or am I the only one?

 

[arbiter]

for HDD's cache helps with write speeds but for SSD's they are usually fast enough cache really doesn't as much anymore hence why don't see advert for them.

 

[PerfectWave]

sadly you need to read the review to know what type of cache and the dimension of the cache for ssd

 

[Shou Miko]

for HDD's cache helps with write speeds but for SSD's they are usually fast enough cache really doesn't as much anymore hence why don't see advert for them.

For SSD's file transfers helps a lot depending on the file size you can read that in a lot of reviews even for installation.

@PerfectWave yeah but not even reviews sometimes does not take a part the SSD to show the cache even the package shows SLC, DRAM or some sort of cache for the SSD.

 

[PerfectWave]

I guess the 1tb A55 has more then 128 mb dram module. I bought 1tb A55 but didnt even have the time to install

 

[tabascosauz]

You often can't really advertise how much NAND a SSD is using as SLC cache. A number of modern SSDs scale the size of their SLC cache depending on what you're doing, the capacity of the drive, and how full the drive is; it's not a fixed size.

As to DRAM, as you've shown with the Silicon Power drive, it's either a DRAM or DRAM-less design, and is quite obvious with photos or accompanying benchmarks. Because the DRAM is for the controller to utilize, not for your data, its size isn't something you can tell from a benchmark, and companies won't be telling you either. It's a bit like a Carplay headunit; we on the forums want to know what sort of SoC is under the hood, but the only really relevant thing for most people will be screen size and acceptable performance.

But with either SLC or DRAM caching, it's never black and white. Some drives have small SLC sizes but have denser TLC stacks that make for better performance on normal NAND, whereas others scale their SLC size to a massive chunk of the NAND, but performance sucks balls when the writes are no longer going into SLC. And then there are the DRAM-less drives that actually perform really decently, because the controller is designed from the ground up to work without DRAM.

 

[Shou Miko]

@tabascosauz but in reviews I can also see file transferring at some points deep low and really low when it's a DRAM-less drive when you transfer data and on drives with DRAM cache sometimes you see it there to but on really larger transfers or you don't even see it at all.

 

[W1zzard]

DRAM-less drive

DRAM-less is only relevant for 4K random write. It has no effect on 512K sequentials

 

[TheLostSwede]

One thing that a lot of people also seem to forget in this discussion, is that the DRAM also holds the mapping table. At least some DRAM-less drives relies on the host RAM to put this mapping table in, so you might end up losing out a chunk of RAM to your SSD if it's DRAM-less. Some models from WD/SanDisk has a tiny bit of DRAM built into the controller, although it's unclear how much it is, but 4-8MB seems to be the extent of it.
This might be an interesting read for those looking to get a DRAM-less drive, as they've tested the specific drive with HMB (Host Memory Buffer) on and off.

The Toshiba/Kioxia BG4 1TB SSD Review: A Look At Your Next Laptop's SSD

www.anandtech.com

DRAM-less is only relevant for 4K random write. It has no effect on 512K sequentials

That doesn't seem quite true if you read the review above. I guess it depends on the controller as well, since that Kioxia drive clearly suffers during sequential writes with HMB off vs on. Even during some sequential reads it seems to have an affect as well.

 

[W1zzard]

Interesting, probably an ocz controller peculiarity. Haven't seen it on other ssds