TIL that SSDs can lose data if left unplugged for long periods of time (only required to hold data up to 1 year), unlike HDDs which as long as the material holds it can take years.

@digitalstefan @djlink
The highest capacity CF car I have is 1G Byte. It's about x3 the area of the 512G Byte SSD. So the cells could be over 2000x bigger. Likely to be more stable.

I have a 1T micro SD Card in an ex-Chromebook running Linux Mint (64K Flash drive). I don't expect much life from it even powered mostly daily, but the contents are on my server, 2x workstations and a "real" laptop. The 2x workstations and laptop each have SSD and an HDD for user data.

@raymaccarthy @djlink Ray, I'm sorry, but do you actually understand how flash memory works? powering on the SSD does exactly *nothing* to the cells until you at least read them (in which case you get a slight read wear on the cell and its neighbors), and you won't increase the charge levels inside a cell unless you erase and rewrite it, which does more damage, so the speed of charge leaking is higher than if you've just let the data alone.

(I mean, you're an EE – so model your gate capacitor!

@funkylab @djlink
There are no ideal options for SSD. That's why I have backups and the user data on my workstations and main laptop is on HDD (conventional, not shingled or helium etc). The OS is easily installed and restored from backup on a new SSD.
The point is that an unused conventional HDD will last for decades. That's unlikely for SSDs or any high capacity SD card, USB stick etc.

@raymaccarthy @djlink I honestly find the opposite to be the case - HDDs can expose mechanical degradations (air barriers, motor bearings) that tend to work against you when you leave them unpowered. But this isn't about HDDs; it's about the myth that powering on an SSD will help data retention.

@raymaccarthy @djlink Ray, I'm sorry, but do you actually understand how flash memory works? powering on the SSD does exactly *nothing* to the cells until you at least read them (in which case you get a slight read wear on the cell and its neighbors), and you won't increase the charge levels inside a cell unless you erase and rewrite it, which does more damage, so the speed of charge leaking is higher than if you've just let the data alone.

(I mean, you're an EE – so model your gate capacitor!

TIL that SSDs can lose data if left unplugged for long periods of time (only required to hold data up to 1 year), unlike HDDs which as long as the material holds it can take years.

Edit: added link: https://www.slashgear.com/1893447/dont-leave-your-old-ssd-unplugged/

@raymaccarthy @djlink I honestly find the opposite to be the case - HDDs can expose mechanical degradations (air barriers, motor bearings) that tend to work against you when you leave them unpowered. But this isn't about HDDs; it's about the myth that powering on an SSD will help data retention.

@funkylab @djlink
NO, the article isn't about powering up SSDs, but they fade in a drawer.
It's proven that HDDs generally don't wear out when powered off. The bearings etc only degrade when they are spinning.
The big plus on SSDs is random access speed, not reliability, for a home user. They are not a backup medium. An SSD in an external USB box is useful for file transfer, not backups.

@raymaccarthy @djlink I'm really not sure where the idea that a powered SSD would be more reliable than an unpowered one – that could only be true if it would be re-writing itself in the background, which would, counter to the intent, make it wear out faster, unless the SSD is essentially unused and the re-writing was free to use arbitrary much rarely or never used pages to copy the data to. But even that would be very undesirable – who wants an SSD with a standby power usage as if written to?)

@raymaccarthy I was reacting to @djlink post, not the article whose authors will never read this.

@raymaccarthy I was reacting to @djlink post, not the article whose authors will never read this.

@funkylab @djlink
No, the main point is that an unpowered SSD isn't reliable compared even to floppies (though they are sensitive to storage conditions). I've had difficulty with 20 to 40 year floppies due to poor storage.
I transferred the MFM HDD contents to IDE HDD over 20 years ago. They are gone.

@funkylab @djlink
Well, you never know who is reading stuff. Or linking.
Some of the ideas in Project Xanadu were interesting.
Anyone remember Bubble Memory? I think a Grid laptop with Plasma screen had it and one was used on a space mission. Didn't Shuttle have 8" floppies?

@raymaccarthy @djlink the statement "if left unplugged" is at best misleading (but really, just a misunderstanding) because data will fade regardless of the SSD being powered or not. And the cited 1 a data retention is also a misunderstanding of test conditions, as overly extensively explained.

@funkylab @djlink
Backups that don't use SSD, helium or shingled HDD etc are good.
I used to have tape but it's easier now to have multiple HDDs in USB boxes.

@raymaccarthy @djlink now you're just listing obsolete storage technologies, (I don't know project Xanadu) which all have many orders of magnitudes worse bit error rates than modern SSDs.

@funkylab @djlink
It's a matter of perspective. Certainly Zip drives were ghastly. I don't know how long term bubble memory was, but there is lots of stuff more reliable than consumer SSDs or 1T micro SD cards. Also the sudden complete loss of an SD card or SSD (256G to 1000 G) compared to errors on one file on a floppy (0.00144G or even 0.0001) are alarming.

@raymaccarthy @djlink that's because of cost per bit, not because of reliability.

@raymaccarthy @djlink you're following nostalgia there, not engineering. you need yo realize that all these ancient storage techniques never amounted to as much storage as your SSD. I'm not even sure there ever was a cumulative Gigabit in bubble storage, and if you read that out, it'd have several thousand errors. Much worse than an SD card left in a desk drawer for a couple of yeara, for sure!

@funkylab @djlink
There were notoriously unreliable tape cartridge systems. Travan?
Customers hated the cost and time to do backups and our insistence that without the time consuming verification how did they know it was a backup?
Also hard to get customers to accept that RAID 1 or 5 was for high availability, that they STILL needed a backup. Ideally also extra copies off site.
I still have an external SCSI tape drive in the attic. It would need about 500 tapes for one backup.