Bronden Neopatus
Aliastra Gallente Federation
24
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Posted - 2014.03.15 20:38:00 -
[32] - Quote
Janden Rynd wrote:I'm not sure why I'm doing this, I really should just let CCP fall on their face here; after all, EVE is a harsh place, right?
Still, in order to make sure people understand how big of a mistake this is, allow me to present a little lesson in physics:
(Disclaimer: I've gotten in trouble before by making assumptions about people's level of understanding. To avoid that, I'm starting out with the most simple principles. This is not meant as an insult to anyone's intelligence; rather it's just me covering my bases)
All substances in this world are made up of tiny atoms. Stable atoms are made up of a number of negatively charged electrons which orbit an equal number of positively charged protons. An electrical charge is created when electrons are moved from one atom to another, causing an imbalance. An atom with an excess of electrons will be negatively charged, and an atom missing electrons will be positively charged.
The thing is that atoms don't like to be unbalanced; so if an atom has more electrons than protons, some of those electrons will eventually move back to an atom that is missing electrons. The rate at which these electrons relocate is dependent largely upon what type of atom they are attached to, and what sort of material they have to pass through. If a large enough charge builds up, this movement of electrons can be very dramatic and quick, such as with lightning. But when the electrons don't have to move through a heavy insulator (like air), they can slowly bleed off without much fanfare.
"That's great Mr. Wizard, but what does that have to do with an SSD as a long-term storage device?"
I'm glad you asked. You see, an SSD is made up of an array of flash memory chips. Flash memory stores data by putting different amounts of electrical charge on lots of individual memory cells. Essentially, an amount of electrons are pushed onto a cell. How many electrons are on a given cell, and therefore how much electrical charge the cell has, translates into a specific data value. So when you go to read information off of the SSD, you are really just checking to see how much electrical charge is on each cell, and then interpreting that charge as data.
The problem is though that, as I said before, atoms don't like to have an unbalanced charge. The electrons pushed into the flash memory cells will gradually move off into the surrounding material. If enough of these electrons migrate off of the cells, it can cause a significant enough of a change in the data value stored in those cells. When this happens, you get data corruption. The information stored on the SSD will no longer be the same as what you originally put on it. In most cases, this means that files become corrupted and can no longer be accessed.
So how long does this take? Well, as I indicated before, the most reliable flash memory on the market is only rated for five years maximum data retention. That assumes of course that you are starting with fresh memory with little to no use; the more the memory gets used, the faster it can degrade. Some memory is only rated for one year of retention after regular use.
There are of course ways to extend this. If the memory is erased, and the data re-written, the charge on the individual cells is removed and reset. This refreshes the memory, essentially putting the full charge back where it was, and buying more time before that charge decays. This can be done manually, by backing up a drive, wiping it, and then reprogramming it from the backup. More recent SSDs have refresh algorithms built in, and they will periodically move data around to different locations in order to extend the storage life.
The obvious problem in this specific case is that in order for any of this data refresh stuff to work, the SSD has to be plugged in to an active computer. If the drive isn't on, and it's not connected to an actively running system, it won't be able to refresh itself. So just putting an SSD under a rock isn't going to help. Unless of course it is wired to a really long SATA cable connecting it to a computer being run in a nearby building.
You can also do redundant data storage by writing multiple copies of the same data to the SSD. In doing this, the copies can be compared against each other, and as long as the same pieces of data haven't become corrupted in each copy, there's a good chance you can recover the complete data after it's been partially corrupted. Still, 25 years is a long time, and I would be highly doubtful that any reasonable amount of redundancy would stand a chance of surviving the kind of charge loss and corruption that would occur after two and a half decades.
The bottom line is that SSDs are a storage device built for performance, not longevity. They can access data at tremendous speeds compared to traditional HDDs, which makes them great for high speed applications like gaming. They are very durable; having no moving parts means that you can shake them and knock them around without damaging heads or spinning platters, which makes them great for mobile devices like laptops or tablets. But they are most definitely not designed for long-term archival data storage, and as such they are an incredibly poor choice for this type of time capsule project.
Seriously CCP, do your homework next time; you'll look less foolish that way.
Very interesting question.... I guess that means that the information within a SSD can't last past 5 years unless it's turned on regularly, isn't that? I wonder how does CCP plan to deal with that...
BTW, from my own experience, regular HD are a lot more durable, I've seen a HD 12 years old work right after plugging it to a computer. |