I have had the pleasure and challenge of learning a lot about flash memory and I must add that the high failure rates are not aberrations, they are more or less expected. When people talk about SSDs they assume they are like hard drives. I.e., they should last several years, unless there is some kind of defect on them.
Well, that is not true. Any flash memory cell is basically limited as to the amount of times it can be written to. This is the result of certain physical properties of the materials used, and cannot be avoided.
This means that any SSD has a limited number of writes on it before it fails. So SSDs will fail and ones that are written to a lot will fail faster. If you use an SSD for virtual memory, for example, you can really speed up your computer (if it does use a lot of virtual memory) but your SSD will fail quickly.
There is generally a three way trade off between cost, storage size and failure rate. So every company would probably strike a slightly different trade off, so it is not surprising one company's drives to last longer than another's. Furthermore, within a single type of drive different times of failure would mostly depend on how much the drive is written to.
In general we should not accuse companies who make drives that fail of making shoddy merchandise (unless they fail way too soon), this is just the nature of flash memory.
No. The firmware on SSDs utilises wear leveling (they also set aside a certain percentage of flash cells for housekeeping), so for the vast majority of people for whom SSDs have failed, the reason is NOT that the flash cells have died. From what I read, the real reason seems to be software bugs in the firmware.
Actually all SSDs have to do this. The failure rate on NAND memory is so high at the higher densities that are being used now, that it would be impossible to ship a drive that didn't do it.
You can learn more about it here[1] - while that is a review of the Vertex 3 (SandForce SF-2500 based SSD) the approach (de-duplication, write load-balancing, etc.) is same for all the controllers out there.
There is another awesome article Anand did explaining all the features of some of these higher end controllers and how much work they actually do, but for the life of me I cannot find it. I'll follow up if I do.
Damn close, but not quite. That article Anand put out during the height of TRIM-gate after discovering the permanent speed-degradation designed into the early drives as they filled up (fixed in all newer controller designs FWIW).
The one I had in my brain was one done after that, it was focused on the SandForce SF-2k series (might have been the 2500) where Anand goes through all of the features in the controller pertaining to data safety. The way it is explained and marketed makes it sound like an SSD will fail once every 15 years, but in reality their failure is horrible... I have no idea why the massive discrepancy. Either these NAND chips are MUCH more volatile than we are being told and Anand's numbers are based on (he has calculations to determine failure rates based on load balancing) or the data parity/recovery systems in these controllers are so insufficient that they underestimate the actual data loss occurring on these things and thus underperform.
Thanks for trying to dig it up though, that article along is certainly worth a read for anyone interested in this topic.
I am very well aware that a flash memory performs wear leveling. However this does not prevent the flash cells from failing, it merely ensures they all fail as late as possible. Wear leveling does not prevent wear it only ensures that wear is generally even between cells.
Well, that is not true. Any flash memory cell is basically limited as to the amount of times it can be written to. This is the result of certain physical properties of the materials used, and cannot be avoided.
This means that any SSD has a limited number of writes on it before it fails. So SSDs will fail and ones that are written to a lot will fail faster. If you use an SSD for virtual memory, for example, you can really speed up your computer (if it does use a lot of virtual memory) but your SSD will fail quickly.
There is generally a three way trade off between cost, storage size and failure rate. So every company would probably strike a slightly different trade off, so it is not surprising one company's drives to last longer than another's. Furthermore, within a single type of drive different times of failure would mostly depend on how much the drive is written to.
In general we should not accuse companies who make drives that fail of making shoddy merchandise (unless they fail way too soon), this is just the nature of flash memory.