4 ms·

"Bit-addressable". I don't think this suffers from the same issues that NAND does with successive writes. The other articles I'm seeing after a quick search als

by rosser 11y ago

"Bit-addressable". I don't think this suffers from the same issues that NAND does with successive writes. The other articles I'm seeing after a quick search also suggest a three order of magnitude increase in write endurance.

wtallis 11y ago
Yes, if you read what I wrote I mentioned the three orders of magnitude increase in write endurance as compared with NAND. But when paired with the three orders of magnitude increase in performance, that means it takes the same number of hours to burn it out. And a NAND device without wear leveling can be burned out in less than a day of heavy use. Bit addressability has absolutely nothing to do with endurance. NOR flash is bit addressable but suffers from the same endurance limitations as NAND, because they're fundamentally the same kind of memory cell, just connected differently.
- davrosthedalek 11y ago
  The thing about bit addressability is not completely true. If you can address memory only in pages, you can have quite a large write amplification, depending on the access pattern. A single byte written may count as $PAGESIZE "written data".
  - wtallis 11y ago
    A lack of bit addressability means that hammering one bit would burn out a whole word/page, but it doesn't affect how many cycles it takes to reach that burn-out point, unless you've got wear leveling. In practice, if you burn out any one bit, you need to retire a chunk of the array at least as large as a cache line. And it's not likely that you'll actually be able to directly hammer a single bit, because the endurance is still low enough to require ECC.
- coldtea 11y ago
  >Yes, if you read what I wrote I mentioned the three orders of magnitude increase in write endurance as compared with NAND. But when paired with the three orders of magnitude increase in performance, that means it takes the same number of hours to burn it out. Only in some bizarro world where "three orders of magnitude increase in performance" also means "we'll write three orders of magnitude more data into it". Loads are about use cases, not about how fast you can fill a disk. If my company produces 1TB analytics info per day it wont suddenly produce 1000TB just because I can write to the disks we buy faster. Of course being able to fill it faster also opens up some new, more heavy, use cases. But for any existing use cases, we'd be writing the SAME data volumes we do now, just 1000 times as fast and with 1000 times the endurace. And even if we write 100 the data we do now, we still get 10 times the endurance.

by rosser 11y ago

wtallis 11y ago

Yes, if you read what I wrote I mentioned the three orders of magnitude increase in write endurance as compared with NAND. But when paired with the three orders of magnitude increase in performance, that means it takes the same number of hours to burn it out. And a NAND device without wear leveling can be burned out in less than a day of heavy use. Bit addressability has absolutely nothing to do with endurance. NOR flash is bit addressable but suffers from the same endurance limitations as NAND, because they're fundamentally the same kind of memory cell, just connected differently.

davrosthedalek 11y ago
The thing about bit addressability is not completely true. If you can address memory only in pages, you can have quite a large write amplification, depending on the access pattern. A single byte written may count as $PAGESIZE "written data".
- wtallis 11y ago
  A lack of bit addressability means that hammering one bit would burn out a whole word/page, but it doesn't affect how many cycles it takes to reach that burn-out point, unless you've got wear leveling. In practice, if you burn out any one bit, you need to retire a chunk of the array at least as large as a cache line. And it's not likely that you'll actually be able to directly hammer a single bit, because the endurance is still low enough to require ECC.
coldtea 11y ago
>Yes, if you read what I wrote I mentioned the three orders of magnitude increase in write endurance as compared with NAND. But when paired with the three orders of magnitude increase in performance, that means it takes the same number of hours to burn it out. Only in some bizarro world where "three orders of magnitude increase in performance" also means "we'll write three orders of magnitude more data into it". Loads are about use cases, not about how fast you can fill a disk. If my company produces 1TB analytics info per day it wont suddenly produce 1000TB just because I can write to the disks we buy faster. Of course being able to fill it faster also opens up some new, more heavy, use cases. But for any existing use cases, we'd be writing the SAME data volumes we do now, just 1000 times as fast and with 1000 times the endurace. And even if we write 100 the data we do now, we still get 10 times the endurance.