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Enterprise SSDs, Powered Off, Potentially Lose Data In a Week
New submitter Mal-2 writes with a selection from IB Times of special interest for anyone replacing hard disks with solid state drives:
The standards body for the microelectronics industry has found that Solid State Drives (SSD) can start to lose their data and become corrupted if they are left without power for as little as a week. ... According to a recent presentation (PDF) by Seagate's Alvin Cox, who is also chairman of the Joint Electron Device Engineering Council (JEDEC), the period of time that data will be retained on an SSD is halved for every 5 degrees Celsius (9 degrees Fahrenheit) rise in temperature in the area where the SSD is stored. If you have switched to SSD for either personal or business use, do you follow the recommendation here that spinning-disk media be used as backup as well?
Data loss in flash cells is probabilisitic, but the standard for wear levelling software is to mark a cell as dead if it can't guarantee holding its contents for a year. There have been some interesting proposals to expose this to the OS - there's a lot of data where even holding it for one day would be fine (e.g. browser caches, swap, other temporary files), so the more worn cells could be productively used for this data.
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The statements are actually completely accurate, but a bit misleading. First, this is about what JEDEC requires, not what actual SSDs deliver. Second, this is when SSDs are stored in idle at 55C. And third the JEDEC requirements for minimum off-time data-retention are only 3 months @40C for enterprise-grade SSDs and only 12 months for consumer SSDs at 30C. These are kind of on the low side, although I have lost some OCZ drives that were off for just about a year. (Never buying their trash again...)
That said, anybody conversant with SSD technology knows that SSDs are unsuitable for offline data storage as data obviously has potentially far shorter lifetimes than on magnetic disks, which in turn again have far shorter data lifetime than archival-grade tape. These is absolutely no surprise here for anybody that bothered to find out what the facts are. Of course, there are always those that expect every storage tech to keep data forever, and those dumb enough to have no or unverified backups and those often on media not suitable for long-term storage. Ignoring reality comes at a price.
My personal solution is mixed HDD/SSD Raid1 and, of course, regular backups.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
Your stuff's cargo container was not heated during shipping. If it was stacked below the deck line, where it was not exposed to the sun, it didn't reach 55C during the journey.
John
Every write, not every read. Reads are satisfied as soon as either drive returns the data. And if the raid controller has a battery or supercap so it can cache writes, you'll almost never notice the difference.
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion.
I might be wrong but isn't it also when the SSD is stored at 55C AFTER having been stress tested at 55C to their endurance rating in terabytes written (page 39) under a given workload?
And even then the cherry picked value was in example data submitted by Intel for unknown hardware and very likely extrapolated and quite possibly meaningless because it wasn't part of the chart targeted for the standard.
The article seems to have totally misrepresented the presentation's purpose: which is to lay out endurance testing methodology/standards.
The only important values were on page 26 where they set the minimum requirements of 40C 8hr/day load/30C 1 year retention for consumer (with a higher error ratio) and 55C 24hr/day load/40C 3 months retention for enterprise (with a lower error ratio.)
And it looks like they haven't actually worked out the consumer workload for testing yet.