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Comment by dale_glass | Hacker News Reader

Maybe not yet, but eventually?

HDD manufacturers do seem to see trouble brewing. Eg, one interesting thing to me is that hard disks are getting more complex. We now have:

* Helium

* HAMR

* SMR

* Dual actuators

Helium and HAMR improve density, but add cost. SMR improves density but results in drives that need special handling. Dual actuators improve performance, but increase points of failure.

Things like HAMR and SMR seem to be a sign that there's not that much more density to squeeze out without taking special measures.

One problem is that as drives get larger and larger, RAID sync times keep on growing. Even assuming faster RPM drives and multiple actuators it seems we're getting quite closer to where this becomes a serious problem.

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I don't get your argument.

Hard drive technology pretty much always got more complex as time goes on. Do you think bits shrink themselves?

20+ years ago, we had "Get Perpendicular" explaining why perpendicular bits were a good idea. https://archive.org/details/get-perpendicular

All future technologies are more complex than our past techs. I mean, should we say that future SSDs are doomed because they're going for 4-bits per cell and 300+ layers of silicon rather than the single-layer single-bit simple designs from 10 years ago?

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.

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.

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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.

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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.

> 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.

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.

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.

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,

Surely they reduce cost. Otherwise they'd not be used. A donkey and cart's cheaper than a haulage truck, but donkeys aren't used much in the haulage business anymore.

Look at the lifetime cost and the capabilities you're buying.

> A donkey and cart's cheaper than a haulage truck

Not when you measure the cost per unit of cargo delivered.

That was their point.

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