5 ms·

Samsung rates their QVO (QLC flash) at about 0.36 DWPD for 5 years which works out to over 600 disk mean writes before failure. Even if we half that that's stil

Samsung rates their QVO (QLC flash) at about 0.36 DWPD for 5 years which works out to over 600 disk mean writes before failure. Even if we half that that's still easily 3x high end HDD's, with superior drive health monitoring and far superior recovery/rebuild performance. TLC Flash is 2-3 times higher than that, and exact endurance depends on the specific drive in question as there's more to endurance than single/double/triple/quadruple bit layering.

formerly_proven 4y ago
It seems to me like initially people were worried about SSD endurance but now nobody seems to care anymore, because endurance hasn't turned out to be a significant issue. In fact, I suspect developers care a lot less about I/O patterns now because 1) the performance impact of bad I/O patterns is still high, but the performance floor is way higher on SSDs, so it basically "doesn't matter" for most 2) for end-user applications, user's don't hear your I/O any more, so how are they going to notice? For example, I have this C:\ SSD on a Windows 10 machine, which has accrued more than 100 TBW (>400 drive writes) in 2-3 years [1], which is pretty much only possible if the system is writing all the time to it (and it is). That's not something you would have done in the spinning rust days, simply because the constant crunchy hard drive noises would have annoyed people. [1] And whaddaya know, that SSD still says it's got 70 % more life in it, so it's probably good for some five years of this, at which point the average PC will go into the dumpster anyway. Success achieved.
- magicalhippo 4y ago
  > endurance hasn't turned out to be a significant issue To be fair, I think it's a bit like y2k. It's not an issue because steps have been taken to mitigate it.
  - Dylan16807 4y ago
    I don't know. Simple correction and wear leveling was required to get off the ground, and that by itself was enough to make early drives have sufficient endurance. The real mitigation work was done in the service of storing more bits per cell, with endurance allowed to slip. So sure effort has been put in, but the alternative wasn't disaster, it was using SLC more.
- Zandikar 4y ago
  > now nobody seems to care anymore, I presume you're talking about layman consumers here. > because endurance hasn't turned out to be a significant issue It used to be a big issue. Keep in mind SSD capacities were pretty small back in the day, with 80-120GB capacities being pretty typical. combined with just less mature overall flash technology meant that per cell endurance was not great, and it lacked the controllers and capacities to do proper wear leveling, so the massive speed boost meant you could burn through even "good" SSD's of the day pretty quick, especially in the days before TRIM and what not where the OS was doing unnecessary excessive writes to disk because it just didn't know how to handle flash. At first, the tech kinda brute forced it's way through this problem by using increased capacities (A 100GB SSD for example will often actually have more than 100GB of RAW storage to account for cell degradation, though to what extent and the nature of the transition flash and controller and DRAM or not and etcetcetc are all compounding factors in exactly how that works out), and then through improved overall endurance, controllers, cache, etc in combination with improved software and OS policies to reduce unnecessary wear to drives. So hasn't really been an issue for a while, but it absolutely was one back in the day, even for the layman with a healthy budget. > That's not something you would have done in the spinning rust days, Yes people did. They didn't really have a choice (unless they're having some fun with RAMdisk or something) + HDD I/O was so much slower that it took orders of magnitude longer. Even when you weren't actively doing something drive intensive, the computer the OS was consistently doing work in the background (remember defragging)? > simply because the constant crunchy hard drive noises would have annoyed people It's wild to me to see so many people share this sentiment. Then again I come from a background of having 8x10k 300GB Velociraptors in my personal workstation back in the day. Those were... Loud. lol.
rasz 4y ago
>0.36 DWPD for 5 years so a mechanical drive running for ~40K hours with ~5% spend writing. >easily 3x high end HDD's how? high end HDD offer 2M MTBF, and with something like HGST 7K6000 you end up with pallet loads being retired at 50K hours run time 100% defect free. >superior drive health monitoring how? SSDs usually just die without any warning >and far superior recovery/rebuild performance you mean recovery/rebuild on a storage box level, because your data on dead SSD is unrecoverable gone forever
- Dylan16807 4y ago
  > how? high end HDD offer 2M MTBF, and with something like HGST 7K6000 you end up with pallet loads being retired at 50K hours run time 100% defect free. The warranty says you only get 75 or 125 full drive writes on the two higher end 20TB drives I looked at. I can't tell you why it's that low, but that's what it says. > how? SSDs usually just die without any warning Sometimes SSDs just die, sometimes they go read-only. Sometimes HDDs just die too. Do you have any numbers?

formerly_proven 4y ago

It seems to me like initially people were worried about SSD endurance but now nobody seems to care anymore, because endurance hasn't turned out to be a significant issue. In fact, I suspect developers care a lot less about I/O patterns now because 1) the performance impact of bad I/O patterns is still high, but the performance floor is way higher on SSDs, so it basically "doesn't matter" for most 2) for end-user applications, user's don't hear your I/O any more, so how are they going to notice? For example, I have this C:\ SSD on a Windows 10 machine, which has accrued more than 100 TBW (>400 drive writes) in 2-3 years [1], which is pretty much only possible if the system is writing all the time to it (and it is). That's not something you would have done in the spinning rust days, simply because the constant crunchy hard drive noises would have annoyed people. [1] And whaddaya know, that SSD still says it's got 70 % more life in it, so it's probably good for some five years of this, at which point the average PC will go into the dumpster anyway. Success achieved.

magicalhippo 4y ago
> endurance hasn't turned out to be a significant issue To be fair, I think it's a bit like y2k. It's not an issue because steps have been taken to mitigate it.
- Dylan16807 4y ago
  I don't know. Simple correction and wear leveling was required to get off the ground, and that by itself was enough to make early drives have sufficient endurance. The real mitigation work was done in the service of storing more bits per cell, with endurance allowed to slip. So sure effort has been put in, but the alternative wasn't disaster, it was using SLC more.
Zandikar 4y ago
> now nobody seems to care anymore, I presume you're talking about layman consumers here. > because endurance hasn't turned out to be a significant issue It used to be a big issue. Keep in mind SSD capacities were pretty small back in the day, with 80-120GB capacities being pretty typical. combined with just less mature overall flash technology meant that per cell endurance was not great, and it lacked the controllers and capacities to do proper wear leveling, so the massive speed boost meant you could burn through even "good" SSD's of the day pretty quick, especially in the days before TRIM and what not where the OS was doing unnecessary excessive writes to disk because it just didn't know how to handle flash. At first, the tech kinda brute forced it's way through this problem by using increased capacities (A 100GB SSD for example will often actually have more than 100GB of RAW storage to account for cell degradation, though to what extent and the nature of the transition flash and controller and DRAM or not and etcetcetc are all compounding factors in exactly how that works out), and then through improved overall endurance, controllers, cache, etc in combination with improved software and OS policies to reduce unnecessary wear to drives. So hasn't really been an issue for a while, but it absolutely was one back in the day, even for the layman with a healthy budget. > That's not something you would have done in the spinning rust days, Yes people did. They didn't really have a choice (unless they're having some fun with RAMdisk or something) + HDD I/O was so much slower that it took orders of magnitude longer. Even when you weren't actively doing something drive intensive, the computer the OS was consistently doing work in the background (remember defragging)? > simply because the constant crunchy hard drive noises would have annoyed people It's wild to me to see so many people share this sentiment. Then again I come from a background of having 8x10k 300GB Velociraptors in my personal workstation back in the day. Those were... Loud. lol.

rasz 4y ago

>0.36 DWPD for 5 years so a mechanical drive running for ~40K hours with ~5% spend writing. >easily 3x high end HDD's how? high end HDD offer 2M MTBF, and with something like HGST 7K6000 you end up with pallet loads being retired at 50K hours run time 100% defect free. >superior drive health monitoring how? SSDs usually just die without any warning >and far superior recovery/rebuild performance you mean recovery/rebuild on a storage box level, because your data on dead SSD is unrecoverable gone forever

Dylan16807 4y ago
> how? high end HDD offer 2M MTBF, and with something like HGST 7K6000 you end up with pallet loads being retired at 50K hours run time 100% defect free. The warranty says you only get 75 or 125 full drive writes on the two higher end 20TB drives I looked at. I can't tell you why it's that low, but that's what it says. > how? SSDs usually just die without any warning Sometimes SSDs just die, sometimes they go read-only. Sometimes HDDs just die too. Do you have any numbers?