MoJo wrote:
Their numbers don't add up either. If the maximum program/erase cycles decreased from 8000 to 5000 that is nearly a 40% reduction, but the amount of spare capacity has not increased by anything like that much. Therefore the drive will fail sooner.
No. At least not if RAISE space reduces write amplification as free space on an Intel SSD does. (I don't know, someone from Sandforce or OCZ would have to confirm this)
Write Amplification is affected by the amount of spare capacity in an SSD. Increasing the spare capacity reduces write amplification in a non linear fashion increasing drive lifetime exponentially.
http://intelstudios.edgesuite.net/idf/2 ... S003/f.htm was a good source but I can't get the video to play since the 2010 presentations went up. If it works for you check it out.
If not I'll quote from another thread where I discussed content from IDF.
Quote:
http://intelstudios.edgesuite.net/idf/2009/sf/aep/IDF_2009_MEMS003/f.htm around the 16 minute mark (slide 19) they took 160GB X-25M Gen 2 drives and formatted them differently and ran them to first failure in an accelerated write scenario a single user wouldn't encounter
Code:
Formatted TB Written
Capacity before failure
160GB 29
144GB 68
128GB 104
_96GB 150
The thing is write amplification means more writes internally than what is reported by the OS so extra free space significantly increases the life expectancy of the flash. The only thing Micron or any other SSD manufacturer has to do to offset 25nm flash lifetime issues is put more in (it offsets the cost advantage but it's worth it because the benefit isn't linear).
from 19 minutes page 21
* Write workload impacts WAF (Write Amplification Factor) and thus endurance
* Increasing transfer sizes of random write workloads generally decreases WAF and increases endurance
* (I'll paraphrase the 3rd bullet) Endurance varies by use and no one can definitively say how long a drive will last. Actual quote "Only way to really forecast what an SSDs endurance will be is to measure it under the targeted workload"
They made it clearer in the 2009 IDF but the presentation is no longer available on the Intel website so I had to pick from data in the 2010 IDF.
Now does the increase in spare area on the 25nm OCZ Vertex 2 exactly offset the decrease in lifetime of 25nm flash as compared to 34nm? I doubt it.
I don't know if it increases
or decreases the lifetime of the drive but I'm willing to say that the life expectancy of the drives due to flash wearing out should change significantly. This could actually be one thing that was improved. Longevity of the flash is either a wash, an improvement no one cares about, or such a minor loss it won't matter to the average user.
The capacity decreased no question about it. The write performance decreased some percentage that needs to be further tested and fully documented. These are the two things to complain about.
And to be clear if Sandforce drives benefit longevity wise from increased RAISE space I'm actually glad that the usable capacity reduced and was dedicated to RAISE. I just wish they had made the new version have a different model # / name.