8 ms·

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 i

by MCRed 11y ago

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 fails. Write leveling and other software efforts work to spread around or eliminate unnecessary writes. But over the practical life of a drive (5-10 years?) being powered off will not cause them to lose data. Edit: I've been following FLASH technology since before the terms "FLASH" was coined, back when it was called EEPROM -- Electrically Erasable Programmable Read Only Memory, an evolution of PROMs (write once) and ERPOMS (erasable with UV light). If there's a myth out there that flash drives just forget things, I'd like to point out that I've had flash drives (low quality at that) from the 1990s that were left for 20 years and then read successfully! Show some citations of real evidence before you down vote me.

cjensen 11y ago
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-retention http://www.anandtech.com/show/9248/the-truth-about-ssd-data-...
- acqq 11y ago
  And AnandTech quotes Intel materials who often boasts to have the most durable drives. Imagine what happens to other ones.
  - philjohn 11y ago
    Samsung back up the 850 Pro with a 10 year/150TB host writes warranty. The trick is moving back 2 processes, which alleviates some of the issues they've faced with the 840 series.
    - acqq 11y ago
      The warranty is certainly not "it will keep the data 10 years without being powered on." We discuss the topic of how long SSDs retain the data when powered off. Intel says, powered off but stored on just 35 degrees C, only 14 weeks, as published by AnandTech: http://images.anandtech.com/doci/9248/3.PNG http://images.anandtech.com/doci/9248/3.PNG And Intel is proud to be more reliable than others. In one of their presentations I've seen they show that they use some very high tech setups (like accelerators!) to measure the degradations fast, and that the other producers fare worse on their tests.
deleted 11y ago
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pgeorgi 11y ago
> flash drives (low quality at that) from the 1990s 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/Presentation/flash_mem_summit_jcooke_inconvenient_truths_nand.pdf https://www.micron.com/~/media/Documents/Products/Presentati... (read disturb on page 19, data retention on page 21)

by MCRed 11y ago

cjensen 11y ago

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

acqq 11y ago
And AnandTech quotes Intel materials who often boasts to have the most durable drives. Imagine what happens to other ones.
- philjohn 11y ago
  Samsung back up the 850 Pro with a 10 year/150TB host writes warranty. The trick is moving back 2 processes, which alleviates some of the issues they've faced with the 840 series.
  - acqq 11y ago
    The warranty is certainly not "it will keep the data 10 years without being powered on." We discuss the topic of how long SSDs retain the data when powered off. Intel says, powered off but stored on just 35 degrees C, only 14 weeks, as published by AnandTech: http://images.anandtech.com/doci/9248/3.PNG http://images.anandtech.com/doci/9248/3.PNG And Intel is proud to be more reliable than others. In one of their presentations I've seen they show that they use some very high tech setups (like accelerators!) to measure the degradations fast, and that the other producers fare worse on their tests.

deleted 11y ago

[deleted]

pgeorgi 11y ago

> flash drives (low quality at that) from the 1990s 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/Presentation/flash_mem_summit_jcooke_inconvenient_truths_nand.pdf https://www.micron.com/~/media/Documents/Products/Presentati... (read disturb on page 19, data retention on page 21)