3 ms·

I can't find any refernces on this. Do you have a link you can share?

by Fargren 15y ago

rkalla 15y ago
Fargren, Actually all SSDs have to do this. The failure rate on NAND memory is so high at the higher densities that are being used now, that it would be impossible to ship a drive that didn't do it. You can learn more about it here[1] - while that is a review of the Vertex 3 (SandForce SF-2500 based SSD) the approach (de-duplication, write load-balancing, etc.) is same for all the controllers out there. There is another awesome article Anand did explaining all the features of some of these higher end controllers and how much work they actually do, but for the life of me I cannot find it. I'll follow up if I do. [1] http://www.anandtech.com/show/4159/ocz-vertex-3-pro-preview-the-first-sf2500-ssd http://www.anandtech.com/show/4159/ocz-vertex-3-pro-preview-...
- parenthesis 15y ago
  Was it this: http://www.anandtech.com/print/2738 http://www.anandtech.com/print/2738 ?
  - rkalla 15y ago
    Damn close, but not quite. That article Anand put out during the height of TRIM-gate after discovering the permanent speed-degradation designed into the early drives as they filled up (fixed in all newer controller designs FWIW). The one I had in my brain was one done after that, it was focused on the SandForce SF-2k series (might have been the 2500) where Anand goes through all of the features in the controller pertaining to data safety. The way it is explained and marketed makes it sound like an SSD will fail once every 15 years, but in reality their failure is horrible... I have no idea why the massive discrepancy. Either these NAND chips are MUCH more volatile than we are being told and Anand's numbers are based on (he has calculations to determine failure rates based on load balancing) or the data parity/recovery systems in these controllers are so insufficient that they underestimate the actual data loss occurring on these things and thus underperform. Thanks for trying to dig it up though, that article along is certainly worth a read for anyone interested in this topic.

I can't find any refernces on this. Do you have a link you can share?

by Fargren 15y ago

I can't find any refernces on this. Do you have a link you can share?

Fargren, Actually all SSDs have to do this. The failure rate on NAND memory is so high at the higher densities that are being used now, that it would be impossible to ship a drive that didn't do it. You can learn more about it here[1] - while that is a review of the Vertex 3 (SandForce SF-2500 based SSD) the approach (de-duplication, write load-balancing, etc.) is same for all the controllers out there. There is another awesome article Anand did explaining all the features of some of these higher end controllers and how much work they actually do, but for the life of me I cannot find it. I'll follow up if I do. [1] http://www.anandtech.com/show/4159/ocz-vertex-3-pro-preview-the-first-sf2500-ssd http://www.anandtech.com/show/4159/ocz-vertex-3-pro-preview-...

parenthesis 15y ago
Was it this: http://www.anandtech.com/print/2738 http://www.anandtech.com/print/2738 ?
- rkalla 15y ago
  Damn close, but not quite. That article Anand put out during the height of TRIM-gate after discovering the permanent speed-degradation designed into the early drives as they filled up (fixed in all newer controller designs FWIW). The one I had in my brain was one done after that, it was focused on the SandForce SF-2k series (might have been the 2500) where Anand goes through all of the features in the controller pertaining to data safety. The way it is explained and marketed makes it sound like an SSD will fail once every 15 years, but in reality their failure is horrible... I have no idea why the massive discrepancy. Either these NAND chips are MUCH more volatile than we are being told and Anand's numbers are based on (he has calculations to determine failure rates based on load balancing) or the data parity/recovery systems in these controllers are so insufficient that they underestimate the actual data loss occurring on these things and thus underperform. Thanks for trying to dig it up though, that article along is certainly worth a read for anyone interested in this topic.