Samsung 840 250gb SSD for 50 quid about $75.

Discussion in 'Hot Deals - Find a Great Deal? Share It Here.' started by lenshoarder, Aug 31, 2013.

  1. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
  2. Reflector

    Reflector Mu-43 Veteran

    406
    Aug 31, 2013
    I wouldn't trust those, not even if they were mounted on a 10ft/3.3m pole. TLC NAND is bad news for reliability and this ignores how SSDs actually don't go into a read only failure mode.

    RAID striping those will also make you suffer write amplifications up the wazoo on a comedic levels of bad.

    Otherwise for scratch disks those would be great for burning through.
     
  3. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    People said the same of MLC NAND when it came out. The computer I'm typing on now has been running RAID MLC NAND for almost 4 years. I actively use it about 16 hours a day. Not even a hickup. The reality is that a modern SSD will out last a HD. Yes, there are people that say their SSD died in a month. There are people that say the same for their HDs. People can say the same about everything. It happens. That's why you should backup. You can get a 1TB HD to back up your 1TB SSD RAID for about $50 these days. $50 is not much to pay for peace of mind.
     
  4. Reflector

    Reflector Mu-43 Veteran

    406
    Aug 31, 2013
    I own a MLC NAND SSD (A Crucial m4 128gb if anyone is curious) which I use exclusively for data caching myself (For random read speed enhancement). I wouldn't trust my OS on it regardless.

    If anything, I've seen data recovery engineers horrified by the sudden failure modes of non enterprise SSDs. If anything, enterprise HDDs are still outlasting consumer SSDs. Not from NAND failure but when the controller or power components on the SSD goes. Or the flash translation layer decides to get burped at by the controller and the SSD becomes effectively bricked.

    MLC NAND at larger node sizes still had 30k+ cycles if it wasn't the low bin grades. As you drop in feature size and then go TLC, you start dropping into the "sub 1k" write cycle region fast. This isn't just fearmongering but if you look at the actual estimates, 3k is on the idealized end. Watch what happens with quality variation and how the definition of write cycle is defined for some NAND ("So long as the 1st sector can survive #k write cycles, everything else like data retention is irrelevant.")

    1TB array backups still take a loooooooooong time, especially if you aren't imaging the array in one giant sequential write. You're talking about hours and hours of downtime if you want to do the array as an image. Otherwise watch as your HDD drops to a halt when small files are copied over one by one.
     
  5. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    You are leaving out big factors like wear leveling. Even assuming 1000 write per node, with wear leveling on a 250GB, the lifetime can be years to decades depending on use. Still more than a HD. Samsung has stated that their new TLC NAND drives will outlast their last generation MLC NAND drives.

    1TB backups only takes a long time if you do a complete copy each time. Who does that? Do a differential. Doesn't take very long at all. Regardless of what you use as your primary, the biggest risk you take is by not backing up.
     
  6. Reflector

    Reflector Mu-43 Veteran

    406
    Aug 31, 2013
    Samsung can make as many claims as they want to sell drives, but the actual world of storage and data recovery can provide you NAND specsheets that would horrify you with concepts like "limited write endurance" being used as a word. If anything wear leveling would mean you burn through your backup sectors in this case.

    If you missed it: You cannot assume 1k writes per node. Maybe you can assume 1k cycles at a certain level but there is no way the entire NAND chip will be homogenous in endurance. That number usually goes towards the "at best" side, not average endurance.

    Differentials still need to check files with different last modified times. When you do this you're still suffering from the HDD being pushed into the zone of very small reads and choking your system down.
     
  7. MitchHamilton

    MitchHamilton Mu-43 Regular

    40
    Feb 16, 2010
    Banff, Alberta, Canada
    No longer available so the point is moot.
     
  8. MAubrey

    MAubrey Photographer

    Jul 9, 2012
    Bellingham, WA
    Mike Aubrey
  9. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    So you don't believe Samsung when they say that their TLC drives will last longer than their MLC drives yet you want me to look at their spec sheets? Ah... OK. People have used "limited write endurance" when talking about SSDs since day one. That doesn't change the fact that SSDs will outlast HDs and can outlast the lifetime of their users.

    I'm not assuming 1K writes. I said that merely because you said that so I went with that assumption. Personally, I think your assertion that it's limited to 1K writes is low.

    Why would checking file modification times take a long time involving many small reads? In most file systems the metadata is not stored in the file, it's stored in a separate structure. That structure can be one long file. So even if you have a 1,000,000 files in a directory, it's just one quick read. Checking file modification times doesn't take very long at all. It takes less time to check my 1.5TB then it took for me to write this response. I don't consider that suffering. Most people can do a differential backup everyday by clicking start and then having dinner. It'll be done by the time they're done. Where's the hardship?
     
  10. Reflector

    Reflector Mu-43 Veteran

    406
    Aug 31, 2013
    If you look at the SSD endurance testing at XtremeSystems the failure modes are are extremely disturbing and the sudden failure early on not from the NAND but controller failure

    This ignores read disturbs and how the controller will refresh the data every # of reads to prevent data retention issues down the line.

    Last modified time checking would be fairly relevant if you actually run checksums on the files during the diff.

    I don't understand why there is a denialist attitude towards SSD reliability when there is clearly professional data showing otherwise from professional sources (Go ahead and ask data recovery companies on this). If anything, it seems the marketing has won here about how SSDs are magical devices that are pure magic and magicialness.

    Also I would like to see a SSD that will outlive me, because if such a thing exists for a low cost and can survive with insane data retention I would be blown away. I mean if such a thing existed I would call all my friends using their enterprise SSDs up in their bladecenters and go "hey guys wait until I tell you how much money you wasted on those SSDs..."
     
  11. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    If it's controller failure, then it doesn't matter if it's SLC, MLC or TLC NAND then. So why wouldn't you touch a TLC NAND with a "10ft/3.3m pole"? The type of NAND doesn't matter.

    No denialist attitude, just reality. For every article you find talking about he dangers of SSDs, you can find one that will say otherwise. Thus I'll turn that around ask why there is such a denialist attitude about SSD reliability.

    You want a SSD to outlive you? Not hard to find. SSD longevity goes up with size. You can get 512GB ones commonly now. Look at this chart and extrapolate up. Even the 160GB one could do the trick.
     

    Attached Files:

  12. Reflector

    Reflector Mu-43 Veteran

    406
    Aug 31, 2013
    SSD Write Endurance 25nm Vs 34nm
    A real life pure write endurance test, this ignores the joy of having a normal system and read disturbs.

    SSD drives is it worth to use in everyday life ? : Flash storage, SSD
    A forum made of lots of data recovery professionals

    The reason I bring up the denialist attitude is how consumers tend to take SSDs as purely all the joy brought to them by marketing, as if there were no problems for engineers to design around. It is odd you ignore read disturbs and write amplification which are actual, known problems to reducing SSD life (Wherein a 1mb write does not actually equal a 1mb write but 8mb+. Using a simplified 1.75x value through the lifetime of the drive does not fly.)

    As humoring as that chart appears, why does media wearout still occur in a professional environment? By that logic, I mean we can just forget about the enterprise grade SLC NAND with actual 100k write cycle lifetime and just shove the lowest grade binning of MLC NAND in a SD card with 128GB of space and hope for the best.

    I mean if anything that chart is basically the same quotable material you can find from SSD marketing materials, ignoring all real problems and replacing them with simplistic formulas simplifying lifetimes instead of actually including real life variables in. I guess I could design aircraft with the assumption that they will fly in a perfect vacuum around a perfect sphere littered with spherical cows then.

    Some fun papers, from Micron
    http://download.micron.com/pdf/technotes/nand/tn2917.pdf
    https://www.micron.com/~/media/Docu...em_summit_jcooke_inconvenient_truths_nand.pdf

    And the latter there is actually in 2007, back when the feature size was larger and gave you much, much higher rewrite cycles and insane data retention compared to today's NAND which actually needs the controller to refresh it else you end up with a drive in a closet that decided to have your data dissipate just like the electrons inside. Isn't quantum tunneling fun?
     
  13. huai

    huai Mu-43 Regular

    77
    May 24, 2013
    I have a Samsun 830 (previous generation of this) and it's the fastest SSD I've used. I haven't had any reliability issues in the past 2 years of using it. Would have jumped on this instantaneously if it was in the US.
     
  14. twokatmew

    twokatmew Mu-43 All-Pro

    Jun 1, 2012
    Lansing, MI, US
    Margaret
    I've got an 840 in my desktop as my boot/system drive. Love it. I'd pick up a 256GB for my laptop, but I don't want to spend the ~$180 right now. Blew my h/w budget for a couple months now. :eek:

    Sent from my Nexus 7 using Tapatalk 4
     
  15. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    I don't see how those threads support your attitude about SSDs. In fact they highlight how conservative that "humoring" "marketing" chart, as you call it, is. To quote from the link you posted.

    "Work PC -- Cruncher #2 ... Crucial M225 64GB SSD Donated to Endurance Testing (Died at 968 TB of writes...no that is not a typo!)"

    Based on that the worst case scenario using the stipulations on that chart, that would be a 264 year life.

    You seem to be basing your opinion on wall clock longevity based on people who are trying to destroy a disk by artificially writing out up to 10's of TBs a day. That is most assuredly not the type of bandwidth even heavy users would have. Who does the equivalent of completely erasing and rewriting their disk a 100 times a day?
     
  16. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    Amazon ships globally. Amazon UK ships to the US. They even eliminate the VAT at checkout.