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Comment by snowwrestler | Hacker News Reader

SSDs need to be powered up fairly often to maintain data integrity. So, they're great for the drives in computers, but for external or backup drives--which might only be powered up occasionally, spinning magnetic disks will still be a better choice for a while, it seems.

edit: maybe not. Bringing this article up from samcheng's post below:

http://www.anandtech.com/show/9248/the-truth-about-ssd-data-...

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Maybe not.

http://www.itworld.com/article/2921047/hardware/no-you-wont-...

Note that that "proof" is not proof at all. Ignoring that it's anecdotal evidence on the sample of one, the author didn't have the checksum of the data on his SSD and didn't try to recompute it, he just tried to boot the computer with the SSD after being turned off for some time and then installed the new OS.

Note that the older the SSD (from the technology standpoint) the better retention is to be expected as the miniaturization of the data cells (which sinks the costs and increases the capacity) significantly lowers the chances for the retention. So his old SSD can behave better than the new one. And some lost bits don't mean that he can't boot, as long as it's just on the places that don't change the behavior.

More anecdotal evidence.

I have two very old SSD. They are the 4 and 16 GB SSD of the early EEEPC 900 Linux version https://en.wikipedia.org/?title=Asus_Eee_PC#Eee_900_series

Needless to say, that netbook stays shut down for months but it still works when I turn it on. It survived many summers at 30 C. I don't know which kind of SSD it contains but being from 2008 it shouldn't be anything too fancy.

As I've said, the older SSD (technologically) and the lower capacity it has the better retention is expected. My 256 MB USB stick also still works, but one I've bought much later, 16 GB, died after only one summer of being not used. And that anecdote too really doesn't prove anything. The worst events are when just a few bits are changed and you don't recognize. Then a few bits more are changed... etc

Do you have a source for this? Just curious.

https://blog.korelogic.com/blog/2015/03/24

The title is pure irony ("SSD Storage - Ignorance of Technology is No Excuse"). See an another link posted here. Also from personal experience I have had no problem with an SSD that wasn't powered for 7 days.

The author of that piece is actually somewhat confused about how SSDs work. Data retention is a matter of the charge store leaking. An SSD doesn't have any means of refreshing that charge on it's own, the same timer is there whether the drive is on or off. And in fact it will lose data faster if the drive is on since then the drive temperature will be higher. Luckily this sort of data loss isn't a big deal in practice for the reasons outlined elsewhere in this thread.

This problem is overblown. A new SSD should be expected to have 10 years of data retention, according to:

http://www.anandtech.com/show/9248/the-truth-about-ssd-data-...

The problem has to do with the temperature you write at and the temperature you store it at. If, for some reason, you're writing in a very cold environment and storing in a very hot one the lifespan is diminished. If it's the opposite, you're golden.

pmontra and Bill_Dimm (edit: and cjensen!) post contradictory blogspammish articles (through no fault of their own - what else is out there?) which both reference the same JEDEC slideshow which has popped up a few times in the last few months.

This is an important enough topic that I wish a better reference existed.

So what if they have to be brought up once in a while? Who cares? They use so little power, that's really not an issue to bring the drive online, even frequently.

I think that we'll just see magnetic disks go away, and tapes pick up the long-term storage market. Pretty much nothing happens when you drop a box of tapes.

How do SSDs refresh their cells? Is that just a normal write as with DRAM?

Wonder if you can refresh SSDs without having that go towards the write counter.

Seems pretty plausible that we could create an SSD that would power up on a timer then couldn't we? Am I missing something?

Backup drives stored in a vault probably don't have access to electricity.

Because that's a plausible, common use case.

Uh, where do you store your backups? Because having them in a safe deposit box is a very common option (amongst those people who actually do backups)

> Likewise, DVD-type archive storage will need a magic trick or two to remain in the race. A terabyte of DVDs will cost more than a terabyte SSD and that isn’t including the DVD library unit.

The article thinks that SSDs will be used for archives.

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