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Unpowered SSDs slowly lose data

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Re: Unpowered SSDs slowly lose data

#291

Post by mywittyname »

adrian_b wrote: post #196
londons_explore wrote: post #155

Earlier quoted context omitted.

I'm sad that drives don't have a 'shutdown' command which writes a few extra bytes of ECC data per page into otherwise empty flash cells. It turns out that a few extra bytes can turn a 1 year endurance into a 100 year endurance.

There are programs with which you can add any desired amount of redundancy to your backup archives, so that they would survive corruption that does not affect a greater amount of data than the added redundancy. For instance, on Linux there is par2cmdline. For all my backups, I create pax archives, which are then compressed, then encrypted, then expanded with par2create, then aggregated again in a single pax file (the…

This is fine, but I'd prefer an option to transparently add parity bits to the drive, even if it means losing access to capacity.

Personally, I keep backups of critical data on a platter disk NAS, so I'm not concerned about losing critical data off of an SSD. However, I did recently have to reinstall Windows on a computer because of a randomly corrupted system file. Which is something this feature would have prevented.

Re: Unpowered SSDs slowly lose data

#292

Post by aidenn0 »

userbinator wrote: post #77

One key point about retention which is not often mentioned, and indeed neither does this article, is that retention is inversely proportional to program/erase cycles and decreases exponentially with increasing temperature. Hence why retention specs are usually X amount of time after Y cycles at Z temperature. Even a QLC SSD that has only been written to once, and kept in a freezer at -40, may hold data for several de…

On the other hand when capacity goes up, the cycle-count goes down for the same workload. A 4TB drive after 1K cycles has written the same amount of data as 100GB drive after 40K cycles.

Re: Unpowered SSDs slowly lose data

#293

Post by casenmgreen »

adrian_b wrote: post #196
londons_explore wrote: post #155

Earlier quoted context omitted.

I'm sad that drives don't have a 'shutdown' command which writes a few extra bytes of ECC data per page into otherwise empty flash cells. It turns out that a few extra bytes can turn a 1 year endurance into a 100 year endurance.

There are programs with which you can add any desired amount of redundancy to your backup archives, so that they would survive corruption that does not affect a greater amount of data than the added redundancy. For instance, on Linux there is par2cmdline. For all my backups, I create pax archives, which are then compressed, then encrypted, then expanded with par2create, then aggregated again in a single pax file (the…

Thank you for this.

I had no knowledge of pax, or that par was an open standard, and I care about what they help with. Going to switch over to using both in my backups.

Re: Unpowered SSDs slowly lose data

#294

Post by KPGv2 »

> SSDs have all but replaced hard drives when it comes to primary storage.

Really? I could have sworn that primary storage was the one place they weren't going to replace HDDs. Aren't they more of a thing for cache?

I've aged and busied myself beyond keeping track of this stuff anymore. I'm going to buy a packable NAS in the next couple months and be done with it. Hopefully ZFS since apparently that's the bee's knees and I won't have to think about RAIDs anymore.

Re: Unpowered SSDs slowly lose data

#295

Post by thebiss »

DeepSeaTortoise wrote: post #180
consp wrote: post #166

Earlier quoted context omitted.

Blind question with no attempt to look it up: why don't filesystems do this? It won't work for most boot code but that is relatively easy to fix by plugging it in somewhere else.

You can still do this for boot code if the error isn't significant enough to make all of the boot fail. The "fixing it by plugging it in somewhere else" could then also be simple enough to the point of being fully automated. ZFS has "copies=2", but iirc there are no filesystems with support for single disk erasure codes, which is a huge shame because these can be several orders of magnitude more robust compared to a…

zfs can run with a single disk stripe. pfsense gladly runs this way. See https://docs.netgate.com/pfsense/en/latest/install/install-z...

Re: Unpowered SSDs slowly lose data

#296

Post by theragra »

amiga-workbench wrote: post #285
theragra wrote: post #282

Earlier quoted context omitted.

I had an LCD that worked from around 2005 to 2022. It became very yellow closer to 2022 for some reason. It was Samsung PVA, I think it was model 910T.

Its old enough to use a CFL backlight and those turn yellow with age.

Thanks ;)

Re: Unpowered SSDs slowly lose data

#297

Post by carra »

We may be facing a grim situation in a few years because of this. Right now most consumer-grade storage is flash memory, and all of it suffers from this problem. SSDs, pendrives, SD cards, Compact Flash... Apparently games for the Nintendo 3DS and PS Vita are already suffering from this, and people losing photos in faulty SDs is hardly news.

Re: Unpowered SSDs slowly lose data

#298

Post by immibis »

cogman10 wrote: post #289
jeremyvisser wrote: post #218

Earlier quoted context omitted.

Here’s the thing. That SSD controller is the interface between you and those blocks. If it decides, by some arbitrary measurement, as defined by some logic within its black box firmware, that it should stop returning all blocks, then it will do so, and you have almost no recourse. This is a very common failure mode of SSDs. As a consequence of some failed blocks (likely exceeding a number of failed blocks, or perhaps…

I really wish this responsibility was something hoisted up into the FS and not a responsibility of the drive itself. It's ridiculous (IMO) that SSD firmware is doing so much transparent work just to keep the illusion that the drive is actually spinning metal with similar sector write performance.

Linux supports raw flash, called an MTD device (memory technology device). It's often used in embedded systems. And it has MTD-native filesystems such as ubifs. But it's only really used in embedded systems because... PC SSDs don't expose that kind of interface. (Nor would you necessarily want them to. A faulty driver would quietly brick your hardware in a matter of minutes to hours)

Re: Unpowered SSDs slowly lose data

#299

Post by immibis »

consp wrote: post #166
londons_explore wrote: post #155

Earlier quoted context omitted.

I'm sad that drives don't have a 'shutdown' command which writes a few extra bytes of ECC data per page into otherwise empty flash cells. It turns out that a few extra bytes can turn a 1 year endurance into a 100 year endurance.

Blind question with no attempt to look it up: why don't filesystems do this? It won't work for most boot code but that is relatively easy to fix by plugging it in somewhere else.

You can, but only if your CPU is directly connected to a flash chip with no controller in the way. Linux calls it the mtd subsystem (memory technology device).

Re: Unpowered SSDs slowly lose data

#300

Post by userbinator »

Aurornis wrote: post #249
userbinator wrote: post #168

Earlier quoted context omitted.

4 times less capacity but 100x or more endurance or retention at the same price looks like a great deal to me. Alternatively: do you want to have 4x more capacity at 1/100th the reliability? Plenty of people would be willing to pay for SLC mode. There is an unofficial firmware hack that enables it: https://news.ycombinator.com/item?id=40405578 1TB QLC SSDs are But why won't the manufacturers let you choose? The real…

> Alternatively: do you want to have 4x more capacity at 1/100th the reliability? If the original drive has sufficient reliability, then yes I do want that. And the majority of consumers do, too. Chasing absolute extreme highest powered off durability is not a priority for 99% of people when the drives work properly for typical use cases. I have 5 year old SSDs where the wear data is still in the single digit percent…

The only positive is that the files are still intact

WTF? That is the only reason to have non-volatile storage.

faster, bigger

I don't care one bit if it doesn't hold data long enough to not worry about while off. Otherwise it's just like RAM.

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