4 ms·

I mean they're not straightforward improvements, they all have some sort of tradeoff. SSDs are getting more complex but at least from my point of view unnotice

I mean they're not straightforward improvements, they all have some sort of tradeoff. SSDs are getting more complex but at least from my point of view unnoticeably so. Yeah, it has 4 bits per cell and 300 layers, but as an user I don't have to think about it. I went from 240 GB to 2 TB and it was an improvement by all parameters. Speed got faster, size got bigger. No downsides whatsoever. SMR on the other hand is absolutely infuriating when you bump into its limitations. It's not automatically better, it's extra capacity with a tradeoff.

dragontamer 3y ago
TLC and QLC has far worse durability than SLC or MLC. There's tradeoffs everywhere. IMO, I stick with the "last generation", because the new stuff almost always has stability and/or data-loss issues. Even top-end Samsung drives on the newest tech seems to lose data. Or the SanDisk loss-of-data problem on their SSD drives. --------- https://www.theverge.com/22291828/sandisk-extreme-pro-portable-my-passport-failure-continued https://www.theverge.com/22291828/sandisk-extreme-pro-portab... The only reason why TLC became usable was because new load-balancing algorithms would keep track of which bits were being erased (each erasure uses up your drive's limited durability). It would then have a mini-computer analyze which cells were least used (aka: load-balancing) and move your data over to the less used sections of the drive. Furthermore, drives would compress the data to minimize writes (and therefore erasures). Its not exactly a simple technology, and a lot of things have gone wrong in practice. -------- When your software says "Write to SSD-location #10,000", it _DOESN'T_ write there. It enters the load balancing algorithm, it finds a new location that has least been used. It pretends that new location is #10,000. It sets the "old Location-10,000" to the TRIM state, and then the OS runs a garbage collector over your data at some future point to keep this whole scheme working.
- bitwize 3y ago
  > It would then have a mini-computer analyze which cells were least used (aka: load-balancing) I'm imagining a PDP-11 dedicated to controlling and wear-leveling an array of flash chips, and smiling. The idea is not quite as silly as you might think; there are real, actual PDP-11s still running RTOSes and "embedded" applications like nuclear power plant monitoring/control... some of which will be supported until the 2050s at least.
- vidarh 3y ago
  Wear-levelling ins't new, though. It has been a thing as long as flash has. Translation layers for wear levelling were not new when I last worked on drivers for a flash device 25 years ago.
  - dragontamer 3y ago
    Specific implementations, errors, and data-loss associated with those wear-leveling algorithms change every new firmware version of drives. Each generation adds new features to the SSD firmware that I don't necessarily need, that will change wear-leveling (and other such details). Then 6 months later, we learn that Sandisk Extreme was the drive with the messed up firmware. Or the "Slow Reads" from the Samsung 840.
    - vidarh 3y ago
      Yes, but the point is that this is "business as usual" with flash, nothing new. Wear levelling methods were patented at least as early as 1991, and FTL drivers were available for Linux at least by the late 90's to handle "dumb" flash that didn't have their own wear levelling built in. I absolutely agree with your other point of sticking to older, well tested drives,

dragontamer 3y ago

TLC and QLC has far worse durability than SLC or MLC. There's tradeoffs everywhere. IMO, I stick with the "last generation", because the new stuff almost always has stability and/or data-loss issues. Even top-end Samsung drives on the newest tech seems to lose data. Or the SanDisk loss-of-data problem on their SSD drives. --------- https://www.theverge.com/22291828/sandisk-extreme-pro-portable-my-passport-failure-continued https://www.theverge.com/22291828/sandisk-extreme-pro-portab... The only reason why TLC became usable was because new load-balancing algorithms would keep track of which bits were being erased (each erasure uses up your drive's limited durability). It would then have a mini-computer analyze which cells were least used (aka: load-balancing) and move your data over to the less used sections of the drive. Furthermore, drives would compress the data to minimize writes (and therefore erasures). Its not exactly a simple technology, and a lot of things have gone wrong in practice. -------- When your software says "Write to SSD-location #10,000", it _DOESN'T_ write there. It enters the load balancing algorithm, it finds a new location that has least been used. It pretends that new location is #10,000. It sets the "old Location-10,000" to the TRIM state, and then the OS runs a garbage collector over your data at some future point to keep this whole scheme working.

bitwize 3y ago
> It would then have a mini-computer analyze which cells were least used (aka: load-balancing) I'm imagining a PDP-11 dedicated to controlling and wear-leveling an array of flash chips, and smiling. The idea is not quite as silly as you might think; there are real, actual PDP-11s still running RTOSes and "embedded" applications like nuclear power plant monitoring/control... some of which will be supported until the 2050s at least.
vidarh 3y ago
Wear-levelling ins't new, though. It has been a thing as long as flash has. Translation layers for wear levelling were not new when I last worked on drivers for a flash device 25 years ago.
- dragontamer 3y ago
  Specific implementations, errors, and data-loss associated with those wear-leveling algorithms change every new firmware version of drives. Each generation adds new features to the SSD firmware that I don't necessarily need, that will change wear-leveling (and other such details). Then 6 months later, we learn that Sandisk Extreme was the drive with the messed up firmware. Or the "Slow Reads" from the Samsung 840.
  - vidarh 3y ago
    Yes, but the point is that this is "business as usual" with flash, nothing new. Wear levelling methods were patented at least as early as 1991, and FTL drivers were available for Linux at least by the late 90's to handle "dumb" flash that didn't have their own wear levelling built in. I absolutely agree with your other point of sticking to older, well tested drives,