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Unpowered SSDs slowly lose data

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Re: Unpowered SSDs slowly lose data

#111

Post by fairfeather »

whitepoplar wrote: post #81
fairfeather wrote: post #54

Earlier quoted context omitted.

SSD firmware engineer here. I work on enterprise stuff, so ymmv on consumer grade internals. Generally, the data refresh will all happen in the background when the system is powered (depending on the power state). Performance is probably throttled during those operations, so you just see a slightly slower copy while this is happening behind the scenes. The unused space decaying is probably not an issue, since the int…

How long does the data refresh take, approx? Let's say I have an external portable SSD that I keep stored data on. Would plugging the drive into my computer and running dd if=/dev/sdX of=/dev/null bs=1M status=progress work to refresh any bad blocks internally?

A full read would do it, but I think the safer recommendation is to just use a small hdd for external storage. Anything else is just dealing with mitigating factors

Re: Unpowered SSDs slowly lose data

#112

Post by BrenBarn »

fairfeather wrote: post #54
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,…

SSD firmware engineer here. I work on enterprise stuff, so ymmv on consumer grade internals. Generally, the data refresh will all happen in the background when the system is powered (depending on the power state). Performance is probably throttled during those operations, so you just see a slightly slower copy while this is happening behind the scenes. The unused space decaying is probably not an issue, since the int…

So you need to do an fsck? My big question after reading this article (and others like it) is whether it is enough to just power up the device (for how long?), or if each byte actually needs to be read.

The case an average user is worried about is where they have an external SSD that they back stuff up to on a relatively infrequent schedule. In that situation, the question is whether just plugging it and copying some stuff to it is enough to ensure that all the data on the drive is refreshed, or if there's some explicit kind of "maintenance" that needs to be done.

Re: Unpowered SSDs slowly lose data

#113

Post by boznz »

m0dest wrote: post #102

So, product idea: A powered "cold storage box" for M.2 SSDs. 2 to 8 M.2 slots. Periodically, an internal computer connects one of the slots, reads every byte, waits for some period of time, then powers off. Maybe shows a little green light next to each drive when the last read was successful. Could be battery-powered.

here's a better idea, buy a mechanical hard disk.

Re: Unpowered SSDs slowly lose data

#114

Post by 55873445216111 »

cosmic_cheese wrote: post #89

Is there any type of flash-based storage (preferably accessible to end users) that focuses on long term data retention? If not, that feels like a substantial hole in the market. Non-flash durable storage tend to be annoying or impractical for day to day use. I want to be able to find a 25 year old SD card hiding in some crevice and unearth an unintentional time capsule, much like how one can pick up 20+ year old Mini…

Yes, NOR Flash guarantees 20 years data retention. It's about $30/GiB.

Re: Unpowered SSDs slowly lose data

#115

Post by cobertos »

How does one keep an SSD powered without actually mounting it or working with it? I have backups on SSDs and old drives I would like to keep somewhat live.

Should I pop them in an old server? Is there an appliance that just supplies power? Is there a self-hosted thing I can monitor disks which I have 0 access usage for and don't want connected to anything but want to keep "live"

Re: Unpowered SSDs slowly lose data

#116

Post by whitepoplar »

fairfeather wrote: post #111
whitepoplar wrote: post #81

Earlier quoted context omitted.

How long does the data refresh take, approx? Let's say I have an external portable SSD that I keep stored data on. Would plugging the drive into my computer and running dd if=/dev/sdX of=/dev/null bs=1M status=progress work to refresh any bad blocks internally?

A full read would do it, but I think the safer recommendation is to just use a small hdd for external storage. Anything else is just dealing with mitigating factors

Thanks! I think you're right about just using an HDD, but for my portable SSD situation, after a full read of all blocks, how long would you leave the drive plugged in for? Does the refresh procedure typically take a while, or would it be completed in roughly the time it would take to read all blocks?

Re: Unpowered SSDs slowly lose data

#117

Post by rasz »

gruez wrote: post #58
fairfeather wrote: post #54

Earlier quoted context omitted.

SSD firmware engineer here. I work on enterprise stuff, so ymmv on consumer grade internals. Generally, the data refresh will all happen in the background when the system is powered (depending on the power state). Performance is probably throttled during those operations, so you just see a slightly slower copy while this is happening behind the scenes. The unused space decaying is probably not an issue, since the int…

>Generally, the data refresh will all happen in the background when the system is powered (depending on the power state). How does the SSD know when to run the refresh job? AFAIK SSDs don't have an internal clock so it can't tell how long it's been powered off. Moreover does doing a read generate some sort of telemetry to the controller indicating how strong/weak the signal is, thereby informing whether it should ref…

https://www.techspot.com/news/60501-samsung-addresses-slow-8...

samsung fix was aggressive scanning and rewriting in the background

Re: Unpowered SSDs slowly lose data

#118

Post by nirui »

cobertos wrote: post #115

How does one keep an SSD powered without actually mounting it or working with it? I have backups on SSDs and old drives I would like to keep somewhat live. Should I pop them in an old server? Is there an appliance that just supplies power? Is there a self-hosted thing I can monitor disks which I have 0 access usage for and don't want connected to anything but want to keep "live"

The simplest trick is just don't use SSD for long term backup, use a normal magnetic hard drive instead, those thing way lasts _longer_ (but not forever, even in human timescale).

I have a HDD that was 17+ years since it last powered on. I dug it out recently to re-establish some memories, and discovered that it still reads. But of course you need to take care of them well, put them in an Anti-Static Bag or something similar, and make sure the storage environment is dry.

It's not prefect, but at least you don't have to struggle that much maintaining SSDs.

Re: Unpowered SSDs slowly lose data

#119

Post by Brybry »

cobertos wrote: post #115

How does one keep an SSD powered without actually mounting it or working with it? I have backups on SSDs and old drives I would like to keep somewhat live. Should I pop them in an old server? Is there an appliance that just supplies power? Is there a self-hosted thing I can monitor disks which I have 0 access usage for and don't want connected to anything but want to keep "live"

There are cheap USBPATA/SATA or USBNVME adapters out there that usually also come with 120v AC -> 3/5/12v DC PATA/SATA power supplies (and if the SATA SSDs only need 5v then some adapters might work with USB alone).

I use them for working with old unmounted hard drives or for cloning drives for family members before swapping them. But they would probably work for just supplying power too?

The one I use the most is an 18 year old Rosewill RCW-608.

I don't know if the firmware/controller would do what it needs to do with only power connected. I wonder if there's some way to use SMART value tracking to tell? Like if power on hours increments surely the controller was doing the things it needs to do?

Re: Unpowered SSDs slowly lose data

#120

Post by spoaceman7777 »

A solution I haven't yet seen in this thread is to buy multiple drives, and sacrifice the capacity of one of those drives to maintain single parity via a raidz1 configuration with zfs. (raidz2 or raidz3 are likely better, as you can guard against full drive failures as well, but you'd need to increase the number of drives' capacity that you're using for parity.)

zfs in these filesystem-specific parity-raid implementations also auto-repairs corrupted data whenever read, and the scrub utility provides an additional tool for recognizing and correcting such issues proactively.

This applies to both HDDs and SSDs. So, a good option for just about any archival use case.

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