Comment by forrestthewoods
2 days ago
My tone is a combination of genuine curiosity and moderate annoyance at a dismissive but unhelpful comment.
RootsComment: SSD speed is miraculous! Jorvis: well ackshually is just RAM and tricks that run out Me: your comment provides zero value
I am annoyed by well ackshually comments. I’d love to learn more about SDD performance. How is the ram filled? How bad is perf when you cache miss? What’s worse case perf? What usage patterns are good or bad? So many interesting questions.
Look at this Kioxia Excera drive[0]. It plummets from 6800Mb/s (850MB/s) all the way to 1600Mb/s (200MB/s).
Its not really a well ackshually comment, there's real pitfalls. Especially when doing 4K. RAW 4K is 12Gb/s and would fill 450GB within 5 minutes. ProRes 4444XQ within 10 minutes. ProRes4444 in 40 minutes.
Martinald his comment is right too. By being very inefficient and treating TLC (or even QLC) as single level and only writing one bit to a cell, much higher performance can be extracted. But once you hit the 80% full threshold, the drive starts to repack the last/least used data into multiple bits per cell.
A RAM cache and SLC cache can both speed access times up, act as a write buffer and mask the shuffling of bits, but there is a limit.
Lastly, its kind of ironic to see me portrayed as jaded when someone else is the one pouring out vitriol all over the thread. Ah well.
[0]https://tweakers.net/reviews/12310/wd-sn5000-4tb-ssd-hoe-sne...
> this Kioxia Excera drive[0]. It plummets from 6800Mb/s (850MB/s) all the way to 1600Mb/s (200MB/s).
This is interesting. Thanks!
> Its not really a well ackshually comment, there's real pitfalls
I don’t doubt the existence of pitfalls. But the lack of specificity was quite irritating!
Right? I’m comparing my direct experience of enduring the pain of slower than Christmas HDDs to the incredible speeds of SSDs, and get a well actually it’s not SSDs that are fast blah blah. Look dude, I don’t care about your magic smoke that you’re so smart you know how the smoke is made. I just care that I can transfer data at blisteringly fast speeds. I couldn’t care less about QLC, SLC, or TLC because reading/writing at >2GB/s is all the tender loving care I need. Don’t rain on my parade because you’re jaded.
I haven’t had a spinning platter in my dev machine since I think 2008 or 2009. Even back then an SSD was the single biggest upgrade I’d seen the first 3D accelerator cards in the late 90s. (Oh god I’m old).
More recently we saw SSDs get added to video game consoles and load times are about 4x faster. And that’s with code/data optimized for a spinning plate not an SSD.
I know they aren’t actually magic. But they might as well be! I’d love to hear details on what weird conditions reduce their performance by 10x. That’d be cool and fun to know. Alas.