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Unpowered SSDs slowly lose data

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Re: Unpowered SSDs slowly lose data

#281

Post by wmf »

kvemkon wrote: post #233
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…

NVMe protocol introduced namespaces. Is it not the feature perfect for users to decide themselves, how to create 2 virtual SSDs with TLC and pseudo-SLC-mode, choosing how much space to sacrifice for pSLC?

Most people want to use pSLC as cache or as the whole drive, not as a separate namespace.

Re: Unpowered SSDs slowly lose data

#282

Post by theragra »

lotrjohn wrote: post #108
RachelF wrote: post #83

Earlier quoted context omitted.

Endurance going down is hardly a surprise given that the feature size has gone down too. The same goes for logic and DRAM memory. I suspect that 2035 years time, hardware from 2010 will work, while that from 2020 will be less reliable.

Completely anecdotal, and mostly unrelated, but my NES from 1990 is still going strong. Two PS3’s that I have owned simply broke. CRTs from 1994 and 2002 still going strong. LCD tvs from 2012 and 2022 just went kaput for no reason. Old hardware rocks.

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.

Re: Unpowered SSDs slowly lose data

#284

Post by mbreese »

deltoidmaximus wrote: post #259
mbreese wrote: post #205

Earlier quoted context omitted.

1) you have to have an OS that supports it. 2) even if your OS supports it, you may have difficulty using it for your root volume, so partitioning is probably required. 2a) in your case you may not want to use it on your boot volume which would negate the SSD benefit for you. 3) it is recommended that you have ECC RAM due to the checksums. This isn’t a hard and fast requirement, but it does make you more resilient to…

I'm always surprised how often ZFS is recommended when this comes up but not BTRFS which also has checksumming and scrubs and doesn't suffer some of ZFS's drawbacks of complexity and OS integration.

This is a fair point. I think that the instability of early releases of BTRFS and the (lack of) commitment of especially RedHat made me not spend too much time working with it. The lack of a RAID solution made it not feasible for my purposes for a long time, and I was already quite familiar with ZFS through working with Solaris and FreeBSD. Trust in filesystems is hard won and easily lost[0].

I also think the popularity of FreeNAS especially contributed to the popularity of ZFS.

[0] I still look at XFS skeptically after a crash I suffered nearly 20 years ago. It’s not a rational fear, but it’s still there.

Re: Unpowered SSDs slowly lose data

#285

Post by amiga-workbench »

theragra wrote: post #282
lotrjohn wrote: post #108

Earlier quoted context omitted.

Completely anecdotal, and mostly unrelated, but my NES from 1990 is still going strong. Two PS3’s that I have owned simply broke. CRTs from 1994 and 2002 still going strong. LCD tvs from 2012 and 2022 just went kaput for no reason. Old hardware rocks.

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.

Re: Unpowered SSDs slowly lose data

#286

Post by asveikau »

xhkkffbf wrote: post #262
mrspuratic wrote: post #228

Earlier quoted context omitted.

CD storage has an interesting take, the available sector size varies by use, i.e. audio or MPEG1 video (VideoCD) at 2352 data octets per sector (with two media level ECCs), actual data at 2048 octets per sector where the extra EDC/ECC can be exposed by reading "raw". I learned this the hard way with VideoPack's malformed VCD images, I wrote a tool to post-process the images to recreate the correct EDC/ECC per sector.…

Octets? Don't you mean "bytes"? Or is that word problematic now?

The term octets is pretty common in network protocol RFCs, maybe their vocabulary is biased in the direction of that writing.

Re: Unpowered SSDs slowly lose data

#287

Post by spixy »

rossjudson wrote: post #124
dale_glass wrote: post #46

So on the off-chance that there's a firmware engineer in here, how does this actually work? Like does a SSD do some sort of refresh on power-on, or every N hours, or you have to access the specific block, or...? What if you interrupt the process, eg, having a NVMe in an external case that you just plug once a month for a few minutes to just use it as a huge flash drive, is that a problem? What about the unused space,…

Keep in mind that when flash memory is read, you don't get back 0 or 1. You get back (roughly) a floating point value -- so you might get back 0.1, or 0.8. There's extensive code in SSD controllers to reassemble/error correct/compensate for that, and LDPC-ish encoding schemes. Modern controllers have a good idea how healthy the flash is. They will move data around to compensate for weakness. They're doing far more to…

return value < 0.5 ? 0 : 1;

Re: Unpowered SSDs slowly lose data

#288

Post by ianburrell »

leo_e wrote: post #234

We learned this the hard way with "cold" backups stored in a literal safe. We treated NVMe drives like digital stone tablets. A year later, we tried to restore a critical snapshot and checksums failed everywhere. We now have a policy to power-cycle our cold storage drives every 6 months just to refresh the charge traps. It's terrifying how ephemeral "permanent" storage actually is. Tape is annoying to manage, but at…

I think we should stop considering flash as permanent storage. It is temporary storage that keeps working as long as given power.

I wish there was archival storage something long-lasting and large capacity. That would make a good complement to flash for writing backups and long-lasting data.

Re: Unpowered SSDs slowly lose data

#289

Post by cogman10 »

jeremyvisser wrote: post #218
lazide wrote: post #213

Earlier quoted context omitted.

Huh? The issue being discussed is random blocks, yes? If your entire drive is bricked, that is an entirely different issue.

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.

Re: Unpowered SSDs slowly lose data

#290

Post by DoesntMatter22 »

userbinator wrote: post #147
lotrjohn wrote: post #108

Earlier quoted context omitted.

Completely anecdotal, and mostly unrelated, but my NES from 1990 is still going strong. Two PS3’s that I have owned simply broke. CRTs from 1994 and 2002 still going strong. LCD tvs from 2012 and 2022 just went kaput for no reason. Old hardware rocks.

LCD tvs from 2012 and 2022 just went kaput for no reason. Most likely bad capacitors. The https://en.wikipedia.org/wiki/Capacitor_plague may have passed, but electrolytic capacitors are still the major life-limiting component in electronics.

Looks like that plague stopped in 2007? I have a 8 year old LCD that died out of nowhere as well, So I'm guessing wouldn't be affected by this. Could still be a capacitor issue though
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