Earlier quoted context omitted.
noob question... how do i force a full read?
This is the most straightforward reliable option: > sudo dd if=/dev/sdX of=/dev/null bs=4M status=progress iflag=direct
This.
Unpowered SSDs slowly lose data
261–270 of 341 posts
Re: Unpowered SSDs slowly lose data
#262Earlier quoted context omitted.
The filesystem doesn't have access to the right existing ECC data to be able to add a few bytes to do the job. It would need to store a whole extra copy. There are potentially ways a filesystem could use heirarchical ECC to just store a small percentage extra, but it would be far from theoretically optimal and rely on the fact just a few logical blocks of the drive become unreadable, and those logical blocks aren't c…
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?
Re: Unpowered SSDs slowly lose data
#263One 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…
So AWS S3 Glacier might actually be cold
Re: Unpowered SSDs slowly lose data
#264Earlier quoted context omitted.
Huh. I wonder if this is why I'd sometimes get random corruption on my laptop's SSD. I'd reboot after a while and fsck would find issues in random files I haven't touched in a long time.
It's quite possible. Some SSDs are worse offenders for this than others. I have some Samsung 870 EVOs that lost data the way you described. Samsung knew about the issue and quietly swept it under the rug with a firmware update, but once the data was lost, it was gone for good.
I got bit by this. RMA'd the bad drive and the replacement hasn't had problems (iirc it was made in a different country to the faulty one)
Long thread here:
https://www.techpowerup.com/forums/threads/samsung-870-evo-b...
Re: Unpowered SSDs slowly lose data
#265[dead]
Re: Unpowered SSDs slowly lose data
#266One 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…
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.
I recently found a 1GB USB drive from around 2006 I used to use. I plugged in and most of the files were still readable! There were some that were corrupted and unreadable unfortunately.
Re: Unpowered SSDs slowly lose data
#267Earlier 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…
The mechanism is usually that the SSD controller requires that some work be done before your read - for example rewriting some access tables to record 'hot' data.
That work can't be done because there is no free blocks. However, no space can be freed up because every spare writable block is bad or is in some other unusable state.
The drive is therefore dead - it will enumerate, but neither read nor write anything.
Re: Unpowered SSDs slowly lose data
#268Earlier quoted context omitted.
I concur; in my experience ALL my 24/7 drives from 2009-2013 still work today and ALL my 2014+ are dead, started dying after 5 years, last one died 9 years later. Around 10 drives in each group. All older drives are below 100GB (SLC) all never are above 200GB (MLC). I reverted back to older drives for all my machines in 2021 after scoring 30x unused X25-E on ebay. The only MLC I use today are Samsungs best industrial…
> in my experience ALL my 24/7 drives from 2009-2013 still work today and ALL my 2014+ are dead, As a counter anecdote, I have a lot of SSDs from the late 2010s that are still going strong, but I lost some early SSD drives to mysterious and unexpected failures (not near the wear-out level).
Interesting, what kind where they? Mine where all Intel.
Re: Unpowered SSDs slowly lose data
#269We 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 was talking to a lawyer recently and somehow this subject came up and he confessed he has been scanning and storing all his files onto SSDs for years which he keeps in a safe to meet a 7-year retention requirement.
Re: Unpowered SSDs slowly lose data
#270Earlier quoted context omitted.
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…
I'm seeing threads where even for HDDs people are recommending you mount them yearly to do a full check of the data and to ensure that everything keeps moving freely.
regardless if it actually helps the longevity, it's probably a pretty good way to notice when you need another copy of the data. If you have your precious data on three harddrives and one starts thowing errors during your yearly check, you can get a replacement in good time