Endurance

Samsung isn't quoting any specific TB written values for how long it expects the EVO to last, although the drive comes with a 3 year warranty. Samsung doesn't explicitly expose total NAND writes in its SMART details but we do get a wear level indicator (SMART attribute 177). The wear level indicator starts at 100 and decreases linearly down to 1 from what I can tell. At 1 the drive will have exceeded all of its rated p/e cycles, but in reality the drive's total endurance can significantly exceed that value.

Kristian calculated around 1000 p/e cycles using the wear level indicator on his 840 sample last year or roughly 242TB of writes, but we've seen reports of much more than that (e.g. this XtremeSystems user who saw around 432TB of writes to a 120GB SSD 840 before it died). I used Kristian's method of mapping sequential writes to the wear level indicator to determine the rated number of p/e cycles on my 120GB EVO sample:

Samsung SSD 840 EVO Endurance Estimation
  Samsung SSD EVO 120GB
Total Sequential Writes 4338.98 GiB
Wear Level Counter Decrease -3 (raw value = 35)
Estimated Total Writes 144632.81 GiB
Estimated Rated P/E Cycles 1129 cycles

Using the 1129 cycle estimate (which is an improvement compared to last year's 840 sample), I put together the table below to put any fears of endurance to rest. I even upped the total NAND writes per day to 50 GiB just to be a bit more aggressive than the typically quoted 10 - 30 GiB for consumer workloads:

Samsung SSD 840 EVO TurboWrite Buffer Size vs. Capacity
  120GB 250GB 500GB 750GB 1TB
NAND Capacity 128 GiB 256 GiB 512 GiB 768 GiB 1024 GiB
NAND Writes per Day 50 GiB 50 GiB 50 GiB 50 GiB 50 GiB
Days per P/E Cycle 2.56 5.12 10.24 15.36 20.48
Estimated P/E Cycles 1129 1129 1129 1129 1129
Estimated Lifespan in Days 2890 5780 11560 17341 23121
Estimated Lifespan in Years 7.91 15.83 31.67 47.51 63.34
Estimated Lifespan @ 100 GiB of Writes per Day 3.95 7.91 15.83 23.75 31.67

Endurance scales linearly with NAND capacity, and the worst case scenario at 50 GiB of writes per day is just under 8 years of constant write endurance. Keep in mind that this is assuming a write amplification of 1, if you're doing 50 GiB of 4KB random writes you'll blow through this a lot sooner. For a client system however you're probably looking at something much lower than 50 GiB per day of total writes to NAND, random IO included.

I also threw in a line of lifespan estimates at 100 GiB of writes per day. It's only in this configuration that we see the 120GB drive drop below 4 years of endurance, again based on a conservative p/e estimate. Even with 100 GiB of NAND writes per day, once you get beyond the 250GB EVO we're back into absolutely ridiculous endurance estimates.

Keep in mind that all of this is based on 1129 p/e cycles, which is likely less than half of what the practical p/e cycle limit on Samsung's 19nm TLC NAND. To go ahead and double those numbers and then you're probably looking at reality. Endurance isn't a concern for client systems using the 840 EVO.

Inside the Drives & Spare Area TurboWrite: MLC Performance on a TLC Drive
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  • Oxford Guy - Friday, July 26, 2013 - link

    However, there is also the problem of increasing latency and lifespan from node shrinkage. Reply
  • MrSpadge - Saturday, July 27, 2013 - link

    Agreed: no real drive (read: not a rubbish sale) can touch the price of a 128 GB 840 here in Germany either. Reply
  • MamiyaOtaru - Friday, July 26, 2013 - link

    hell with that I want SLC Reply
  • Notmyusualid - Friday, July 26, 2013 - link

    Me too... Reply
  • Dal Makhani - Thursday, July 25, 2013 - link

    why still a dealbreaker? Unless you write a TON. Its a great drive and you dont really need MLC. Reply
  • Heavensrevenge - Thursday, July 25, 2013 - link

    The worries of TLC is a pretty useless worry. I still have a 32MB Sony flash stick I used around 2003, and its flash memory wasn't rated and wear-leveled like it does nowadays by design and It's not dead nor corrupted somehow lol. If you have a USB stick older than 5 years old or any flash cards for a camera that's a few years old and still working 100% fine when people weren't so uselessly worried about flash endurance, then these drive will pose no problems whatsoever. Reply
  • Oxford Guy - Thursday, July 25, 2013 - link

    I thought the Vertex 2 firmware problems (especially the wake-from-sleep bug) were overblown until I had three of them die. I finally gave up on RMAs because the replacements died, too. Anandtech was so positive about OCZ and its Vertex 2. Funny how the drives didn't turn out to be so great. I don't remember the rave reviews covering the wonderful panic mode, either. Reply
  • HisDivineOrder - Saturday, July 27, 2013 - link

    Lots of people were raving about OCZ back then. Today, it's clear. Friends don't let friends OCZ. Reply
  • Shadowmaster625 - Thursday, July 25, 2013 - link

    Can you test RAPID by cutting power to a pc while doing normal everyday stuff like surfing the web or watching a youtube or loadign a game. I would like to know how likely it is for windows to have an unrecoverable error if it loses power while this cachign solution is active. Reply
  • Spunjji - Friday, July 26, 2013 - link

    I second that request. Reply

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