41–50 of 336 posts
Earlier quoted context omitted.
Do you have a source for this? Just curious.
https://blog.korelogic.com/blog/2015/03/24
Is the hdd demise indeed expected so quickly?
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-...
This is an important enough topic that I wish a better reference existed.
Is keeping a SSD powered on enough to prevent bit rot?
It should have no impact. It really is about write capacity. The little cells can only handle being changed so many times before they wear out. The wearing is a chemical/semi-conductor type problem. It's not like DRAM where keeping power applied keeps the cells "fresh" (and in DRAM it's done literally be refreshing each cell at a certain frequency.) The simple equation is the more times a cell is erased the sooner it…
90s flash is more likely NOR, which doesn't suffer some of the failure modes of NAND.
As for NAND, micron would probably not discuss rumors about their technology as fact: https://www.micron.com/~/media/Documents/Products/Presentati... (read disturb on page 19, data retention on page 21)
Earlier quoted context omitted.
It should have no impact. It really is about write capacity. The little cells can only handle being changed so many times before they wear out. The wearing is a chemical/semi-conductor type problem. It's not like DRAM where keeping power applied keeps the cells "fresh" (and in DRAM it's done literally be refreshing each cell at a certain frequency.) The simple equation is the more times a cell is erased the sooner it…
That's incorrect. Charge leaks very slowly out of cells. It's not a big issue, but it does happen. Powered-on SSD firmware knows about the problem and will maintain the cells. [1] http://www.anandtech.com/show/9248/the-truth-about-ssd-data-...
SSD technology still has a reliability hurdle, you can nuke one in a month if you write to it constantly. Spinning media has much longer read/write durability. Until there is parity its still a bit of an arms race for capacity. Hybrid drives are pretty awful so I don't think they'll stick around. I could see Hierarchical Storage Management make a comeback and an entry to the consumer space, but thats been esoteric at…
False. http://techreport.com/review/27909/the-ssd-endurance-experim...
In fairness to Micron/Crucial, the drives did not lose any data.... but the write bandwidth degraded down to 10MB/s which counts as a failure for most apps. That's the catch in the report you cite: the bandwidth of a used-up drive is so poor that it's hard to actually write enough extra data to fully-fail.
Edit: Burning up an SSD was how I learned that TRIM is unnecessary: even though many parts of the filesystem were stable and never re-written, the bandwidth was even across the entire drive. The firmware noticed that some cells were underused and moved the stable data off them so it could use up the endurance evenly.
In a side-note in the article, the author mentions that Amazon Glacier runs on tape. Although I'm not sure Amazon officially explained the technology, I heard (and read on Wikipedia) that they store data on conventional HDDs, that are however kept "offline". Has anyone here some more knowledge about that?
Earlier quoted context omitted.
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-...
Maybe not. http://www.itworld.com/article/2921047/hardware/no-you-wont-...
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.
Cheapest 1 TB SSD on Amazon: $350 Cheapest 1 TB HDD on Amazon: $40 Expecting a 10x drop in prices in 1 year is ludicrous. Even if the prices follow a pseudo Moore's law and fall by half every 18 months, you're looking at at least 5 years before they reach parity. And in the meantimg HDDs would have gotten cheaper; so expect even more time for parity. In other words: ain't happenin' in 2016.
Experienced the same principle in my life a few weeks ago - I moved to a place described as "gentrifying." Realized a week into staying there that I was one of those people who was actually contributing to its gentrification! By no means was it gentrified, though.
Is keeping a SSD powered on enough to prevent bit rot?
No need to power or refresh, but if you have a cruddy SSD you should keep other backups.
JEDEC specs require that a drive that has used 10% of its rewrite capacity it should hold the data for at least 10 years, and this decreases to when a drive has used 100% of its rewrite capacity it should hold the data for at least one year. So to meet specs a consumer drive should fall in between these timeframes. However, cheaper drives may well not completely meet this spec; this is common for many other manufacturing processes.
The bit rot also depends on many other factors, the most important being temperature (you cannot outwit statistical mechanics). The next one is a combination of hot neutrons causing bit flips from impurities in the material and from cosmic rays, the latter of which can be reduced by choosing better storage locations.
Better controllers could understand the decay modes and read and rewrite data to maximize expected lifetime, so power is needed for maximal expected lifetime.
In practice, all of this is not of much use to everyday people [1]. But if you want to maximize your data retention, study all these issues.
Here's a case the authors claim bit rot happened in three months offline [2].
[1] http://www.anandtech.com/show/9248/the-truth-about-ssd-data-...
[2] http://www.maximumpc.com/jedec-your-ssd-needs-power-source-a...