6 ms·

Don't SSDs have a finite TBW? 50GB of writes everyday (possible on large projects) will consume that in a couple of months.

frizkie 6y ago
They do but it's really large. The Tech Report did an endurance test on SSDs 5-6 years ago [0]. The tests took 18 months before all 6 SSDs were dead. Generally you're looking at hundreds of terabytes, if not more than a petabyte in total write capacity before the drive is unusable. This is for older drives (~6 years old as I said), and I don't know enough about storage technology and where it's come since then to say, but I imagine things probably have not gotten worse. [0]: https://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead/ https://techreport.com/review/27909/the-ssd-endurance-experi...
- yread 6y ago
  > things probably have not gotten worse. I am afraid they did, consumer SSDs moved from MLC (2 bits per cell) to TLC (3) or QLC (4). Durability changed from multiple petabytes to low hundreds of terabytes. Still a lot, but I suspect the test would be a lot shorter now.
  - Dylan16807 6y ago
    The TLC drive in that test did fine. 3D flash cells are generally big enough for TLC to not be a problem. I would only worry about write limits on QLC right now, and even then .05 drive writes per day is well under warranty limits so I'd expect it to be fine. Short-lived files are all going to the SLC cache anyway.
dekhn 6y ago
I've swapped hundreds of terabytes to a terabyte SSD (off the shelf cheapie) with no recognizable problems (the gigapixel panoramas look fine).
- nine_k 6y ago
  SSDs avoid catastrophic write failures by retiring damaged blocks. Check the reported capacity; it may have shrunk :) Before you ever see bad blocks, the drive will expend spare blocks; this means that a new drive you buy has 10% more capacity than advertised, and this capacity will be spent to replace blocks worn by writes.
  - dekhn 6y ago
    Now I'm curious how the kernel responds to having swap partitions resized under it.
    - zlynx 6y ago
      Not quite how it works. The SSD will never have a capacity lower than its rated capacity. For the failures I've seen, once the SSD goes to do a write operation and there's no free blocks left, it will lock into read-only mode. And at that point it is dead. Time to get a new one.
      - dekhn 6y ago
        Now I'm really curious. I took the drive I swapped hundreds of terabytes to, and put it in a server (unfortunately not running a checksumming filesystem) and it ran happily for a year.
  - wtallis 6y ago
    SSDs never shrink the reported capacity in response to defective/worn-out blocks. Instead, they have spare area that is not accessible to the user. The SMART data reported by the drive includes an indicator of how much spare area has been used and how much remains. When the available spare area starts dropping rapidly, you're approaching the drive's end of life.
    - Wowfunhappy 6y ago
      I so happened to know this already, but I must say I've always found the approach somewhat weird. Wouldn't it make more sense to give the user all the available space, and then remove capacity slowly as blocks go bad? I guess they think people would be annoyed? Imagine if we treated batteries like SSDs, not allowing the use of a set amount of capacity so that it can be added back later, when the battery's "real" capacity begins to fall. And then making the battery fail catastrophically when it ran out of "reserve" capacity, instead of letting the customer use what diminished capacity was still available.
bluedino 6y ago
Something like the Samsung EVO 960 (typical mid-range SSD) will take 400TB of writes in it's lifetime. So that's 8,000 days of 50GB writes.
- spullara 6y ago
  Hmmm. Looks like I need to move my temp dir for GeForce instant replay off of my SSD. It records about 1.6GB/5min which is 460GB per day. RAM disk would probably be the best option.
  - reitzensteinm 6y ago
    I'm pretty sure it doesn't record the desktop with instant unless you have specifically set that up, so you'd only be writing to the drive while you're in game.
    - spullara 6y ago
      True, true.
- daemin 6y ago
  At my current job I do at least 150-200GB of writes per day. 50GB for code temporary files, 70+ GB for data files, x2 that for packing them, and then also deleting some of those to make some room to do it again. Also the disk that it's on is over 50% full so that also degrades it faster as there's fewer blocks to wear level with.
nickjj 6y ago
I've had a Crucial 256GB SSD (MX100) since early 2015 and I use it with Windows 10. WSL 2's file system is on there along with Docker, which I've been using full time since then. That means all of my source code, installing dependencies, building Docker images, etc. is done on the SSD. The SMART stats of the drive says it's at 88% health out of 100%, AKA it'll be dead when it reaches 0%. This is the wear and tear on the drive after ~6 years of full time usage on my primary all around dev / video creating / gaming workstation. It's been powered on 112 times for a grand total of 53,152 running hours and I've written 31TB total to it. 53,152 hours is 2,214 days or a little over 6 years. I keep my workstation on all the time short of power outages that drain my UPS or if I leave my place for days. Here's a screenshot of all of the SMART stats: https://twitter.com/nickjanetakis/status/1357127351772012544 https://twitter.com/nickjanetakis/status/1357127351772012544 I go out of my way to save large files (videos) and other media (games, etc.) on a HDD but generally most apps are installed on the SSD and I don't really think about the writes.
- tomc1985 6y ago
  As a counterpoint, I burn-tested several random M.2 NVME drives over a period of a month of 24/7 writes and reads and all but one model failed before the month was up
  - rbanffy 6y ago
    Heat dissipation can be an issue. Writing continuously generates a lot of heat.
    - tomc1985 6y ago
      Part of the purpose of a burn test is to see how it handles temperature under load. We didn't have the option of adding cooling, many of the product installations took place in a hot climate, and nobody wanted to pay for a hardened part... Anyway, my point is that SSD drive reliability varies wildly
      - nwmcsween 6y ago
magicalhippo 6y ago
The larger your SSD the more flash cells you have, so the more data you can write to it before it fails. You can see this from the warranty for example, which for the Samsung 970 EVO[1] goes linearly from 150TBW for the 250GB model up to 1200TBW for the 2000GB model. So if you take the 1000GB model with its 600TBW warranty, you can write 50BG of data per day for over 32 years before you're exhausted the drive write warranty. [1]: https://www.samsung.com/semiconductor/minisite/ssd/product/consumer/970evo/ https://www.samsung.com/semiconductor/minisite/ssd/product/c... (under "MORE SPECS")

frizkie 6y ago

They do but it's really large. The Tech Report did an endurance test on SSDs 5-6 years ago [0]. The tests took 18 months before all 6 SSDs were dead. Generally you're looking at hundreds of terabytes, if not more than a petabyte in total write capacity before the drive is unusable. This is for older drives (~6 years old as I said), and I don't know enough about storage technology and where it's come since then to say, but I imagine things probably have not gotten worse. [0]: https://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead/ https://techreport.com/review/27909/the-ssd-endurance-experi...

yread 6y ago
> things probably have not gotten worse. I am afraid they did, consumer SSDs moved from MLC (2 bits per cell) to TLC (3) or QLC (4). Durability changed from multiple petabytes to low hundreds of terabytes. Still a lot, but I suspect the test would be a lot shorter now.
- Dylan16807 6y ago
  The TLC drive in that test did fine. 3D flash cells are generally big enough for TLC to not be a problem. I would only worry about write limits on QLC right now, and even then .05 drive writes per day is well under warranty limits so I'd expect it to be fine. Short-lived files are all going to the SLC cache anyway.

dekhn 6y ago

I've swapped hundreds of terabytes to a terabyte SSD (off the shelf cheapie) with no recognizable problems (the gigapixel panoramas look fine).

nine_k 6y ago
SSDs avoid catastrophic write failures by retiring damaged blocks. Check the reported capacity; it may have shrunk :) Before you ever see bad blocks, the drive will expend spare blocks; this means that a new drive you buy has 10% more capacity than advertised, and this capacity will be spent to replace blocks worn by writes.
- dekhn 6y ago
  Now I'm curious how the kernel responds to having swap partitions resized under it.
  - zlynx 6y ago
    Not quite how it works. The SSD will never have a capacity lower than its rated capacity. For the failures I've seen, once the SSD goes to do a write operation and there's no free blocks left, it will lock into read-only mode. And at that point it is dead. Time to get a new one.
    - dekhn 6y ago
      Now I'm really curious. I took the drive I swapped hundreds of terabytes to, and put it in a server (unfortunately not running a checksumming filesystem) and it ran happily for a year.
- wtallis 6y ago
  SSDs never shrink the reported capacity in response to defective/worn-out blocks. Instead, they have spare area that is not accessible to the user. The SMART data reported by the drive includes an indicator of how much spare area has been used and how much remains. When the available spare area starts dropping rapidly, you're approaching the drive's end of life.
  - Wowfunhappy 6y ago
    I so happened to know this already, but I must say I've always found the approach somewhat weird. Wouldn't it make more sense to give the user all the available space, and then remove capacity slowly as blocks go bad? I guess they think people would be annoyed? Imagine if we treated batteries like SSDs, not allowing the use of a set amount of capacity so that it can be added back later, when the battery's "real" capacity begins to fall. And then making the battery fail catastrophically when it ran out of "reserve" capacity, instead of letting the customer use what diminished capacity was still available.

bluedino 6y ago

Something like the Samsung EVO 960 (typical mid-range SSD) will take 400TB of writes in it's lifetime. So that's 8,000 days of 50GB writes.

spullara 6y ago
Hmmm. Looks like I need to move my temp dir for GeForce instant replay off of my SSD. It records about 1.6GB/5min which is 460GB per day. RAM disk would probably be the best option.
- reitzensteinm 6y ago
  I'm pretty sure it doesn't record the desktop with instant unless you have specifically set that up, so you'd only be writing to the drive while you're in game.
  - spullara 6y ago
    True, true.
daemin 6y ago
At my current job I do at least 150-200GB of writes per day. 50GB for code temporary files, 70+ GB for data files, x2 that for packing them, and then also deleting some of those to make some room to do it again. Also the disk that it's on is over 50% full so that also degrades it faster as there's fewer blocks to wear level with.

nickjj 6y ago

I've had a Crucial 256GB SSD (MX100) since early 2015 and I use it with Windows 10. WSL 2's file system is on there along with Docker, which I've been using full time since then. That means all of my source code, installing dependencies, building Docker images, etc. is done on the SSD. The SMART stats of the drive says it's at 88% health out of 100%, AKA it'll be dead when it reaches 0%. This is the wear and tear on the drive after ~6 years of full time usage on my primary all around dev / video creating / gaming workstation. It's been powered on 112 times for a grand total of 53,152 running hours and I've written 31TB total to it. 53,152 hours is 2,214 days or a little over 6 years. I keep my workstation on all the time short of power outages that drain my UPS or if I leave my place for days. Here's a screenshot of all of the SMART stats: https://twitter.com/nickjanetakis/status/1357127351772012544 https://twitter.com/nickjanetakis/status/1357127351772012544 I go out of my way to save large files (videos) and other media (games, etc.) on a HDD but generally most apps are installed on the SSD and I don't really think about the writes.

tomc1985 6y ago
As a counterpoint, I burn-tested several random M.2 NVME drives over a period of a month of 24/7 writes and reads and all but one model failed before the month was up
- rbanffy 6y ago
  Heat dissipation can be an issue. Writing continuously generates a lot of heat.
  - tomc1985 6y ago
    Part of the purpose of a burn test is to see how it handles temperature under load. We didn't have the option of adding cooling, many of the product installations took place in a hot climate, and nobody wanted to pay for a hardened part... Anyway, my point is that SSD drive reliability varies wildly
    - nwmcsween 6y ago

magicalhippo 6y ago

The larger your SSD the more flash cells you have, so the more data you can write to it before it fails. You can see this from the warranty for example, which for the Samsung 970 EVO[1] goes linearly from 150TBW for the 250GB model up to 1200TBW for the 2000GB model. So if you take the 1000GB model with its 600TBW warranty, you can write 50BG of data per day for over 32 years before you're exhausted the drive write warranty. [1]: https://www.samsung.com/semiconductor/minisite/ssd/product/consumer/970evo/ https://www.samsung.com/semiconductor/minisite/ssd/product/c... (under "MORE SPECS")