How Many Overwrites?


I decided to hide the NVR I use for my CCTV system in a place where theives would have a heck of time finding it should my house be broken into. Because temperatures can drop to extremely cold levels, I decided that SSD is the way to go for storage. A 500-512GB SSD would give me a little over a week of storage, based on average motion recording, but what I am having a hard time figuring out is how long a MLC SSD will last based on let's say, a complete overwrite every 7-9 days. Has anyone had any experience with this or can expected lifespan be calculated this way? Also, can anyone recommend a quality SATA SSD for this application? I am looking at the OCZ Colossus Series OCZSSD2-1CLS500G and the Kingston SSDNow V+100 SVP100S2B/512GR. Read and write speeds are unimportant for this application, as it is all about low temp survivability and overwrite durability.

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  1. Best answer
    Interesting application. I have thought of this as a good use for an ssd (ie cold temp or high altitude). Certainly one should wait for the 25nm nand drives to come out early next year as price/GB should drop considerably. I have heard a figure of about 30k writes/cell for this new 25nm nand. With wear leveling this can create a significant life span for a drive BUT lets assume you are writing to each and every cell once a week.

    30k weeks. or 280k days is about 767 years. Cut that figure in half to be safe.

    Some nand is guaranteed for only 10k write cycles but we know that even in that worst case scenario most of the cells will last 100k and 90% will likely last 1m cycles.

    So in the very worst case scenario the actual flash memory may fail in little more than 200 years.

    I hope you never have to look at the pictures on this ssd.
  2. Thanks adampower. Great answer. I also hope I never have to review the video for anything other than material to use against my drunken friends :). And even if I get 1% of the lifespan on the drive (7.67 years) before it begins to degrade, I will likely have installed all new hardware by then.
  3. Best answer selected by Mark_Alberta.
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