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Notebooks SSD laptops

Discussion in 'Hardware' started by scq, 7 Jan 2008.

  1. scq

    scq What's a Dremel?

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    It seems like the hottest thing in laptops right now are SSDs. Though they're expensive, they're durable and fast, as well as cool and energy efficient - but I can't help but wonder - doesn't flash memory have a finite number of read and write cycles? What happens when you hit it? I mean, surely, as a HDD you're accessing as often as a primary hard drive, it would get read and written quite often.

    Just wondering.
     
  2. Jumeira_Johnny

    Jumeira_Johnny 16032 - High plains drifter

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    They have wear leveling. and about a 3 year life span, IIRC. Swap file is what kills it really. The reads are no sweat, it's the random writes.
     
  3. ryanjleng

    ryanjleng ...

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    I was actually writing a paper on this yesterday.

    In a nut shell....

    SSD is using NAND SLC technology, which is MUCH... Much... more resistant 100,000+ write cycles, faster, but limited in size and expensive.

    NAND MLC is used in the cheap-o Flash Drive. short lifespan: 5000-10000 write cycles, slower, very cheap, but huge capacity.

    SLC = Single-Level Cell (1bit per cell: Binary)
    MLC = Multi-Level Cell (2bit per cell: Multiple-value)

    SSD uses NAND SLC technology that can be found in industrial Compact Flash (i got 1 installed in my car.). These devices usually have about 2,000,000 write cycles or more.

    The math is a bit like this.

    Assuming OS/you will be writing the SSD the same location every minute (60 writes/hr). Your average usage per day is 8hr (8 x 60 writes/hr = 480 writes/day).

    365 days x 480 writes/day = 175,200 writes/yr

    Based on a lifespan of 2,000,000... that works out to be: 11 years

    Half that time to 5.5 years will allow the OS/you to write to the SSD at a rate of 2-write per min.

    Beyond NAND SLC, the NAND Controller has very sophisticated logics.

    Lastly, some SSD has more write-cycle than 2,000,000 because they have larger than usual redundant/spare bits sitting around, waiting for bit-failure.

    ~~~ figures based on 50nm NAND tech ~~~


    :duh: Arggg.. pain.
     
  4. ryanjleng

    ryanjleng ...

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    Oh, the most amazing benefit of SSD, IMHO is power saving.
     
  5. scq

    scq What's a Dremel?

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    So is NAND SLC 100,000+ or ~2,000,000 because that's a huge range.

    Also, don't forget that when browsing the Internet, stuff is written to the HDD cache constantly, even with caching off.
     
    Last edited: 7 Jan 2008
  6. ryanjleng

    ryanjleng ...

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    50nm NAND SLC single bit is about 100,000+ write cycles.

    But in an actual consumer device, due to the advance controller and logics within - ECC, wear leveling, bit-redundancy, address control mechanism and etc.... NAND SLC write cycles can be stretched further to 2,000,000 write cycles.

    there are specialized algo. that is dedicated to the file allocation table or logical block addressing (LBA) area. This area consistently gets written at a higher rate.

    further more there are proprietary algorithms that's improve the implementation of existing logics.

    as time goes on, the NAND IC fabrication technology will improve the durability.

    as of now... the only thing with SSD is the slower-to-normal transfer rate.
     
  7. steveo_mcg

    steveo_mcg What's a Dremel?

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    Besides that with the volume of ram you now have, if it came to it you could set your cache's to write to a ram disk and only write to the drive if needed. There have been flash based linux systems for years most of the problems have already been worked out.
     
  8. ryanjleng

    ryanjleng ...

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    yes.

    i use SuperSpeed Ramdisk and Caching products. I work with their SuperCache and loving it.
     
  9. airchie

    airchie What's a Dremel?

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    This all sounds awesome, I want an SSD drive for my laptop.

    Have done for quite a while now but can't find them for sale anywhere.

    Anyone seen any retailers with them in stock??? :)
     
  10. warlord2000ad

    warlord2000ad The 20 Year Old Guy

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    Im disappointed SSD have such a short life span, i was looking forward to getting one in a few years when prices dropped.
     
  11. ryanjleng

    ryanjleng ...

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    http://www.google.com/products?q=ssd&btnG=Search+Products&price1=100.00&price2=2,000.00&lnk=prsugg

    lifespan will continuously improve.


    Seeeeriously, shouldn't really get one now... not only because of price.

    jan and mid 08 will be an interesting time to watch SSD.

    wait for at least 12 months. there are things cooking in a few labs. more major brands are coming out soon.

    compression is one thing. parallelistic data path is something else. major efforts are in engineering incremental cost reduction. all these are transparent to the consumers.

    the stars will line up for SSD very soon.
     
  12. airchie

    airchie What's a Dremel?

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    Thanks for the link but I'm looking for UK suppliers of the Samsung sata SSD. :)

    I know its crazy to buy one now and that there's much better ones round the corner, but if I saw one for sale in a UK stockist I don't know if I could keep the credit card under wraps... :D
     
  13. steveo_mcg

    steveo_mcg What's a Dremel?

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    tbh even the current generation of ssh drives will out live the useful life of a magnetic drive. That forty you bought 4 years ago, bout useless isn't it, your ssd may be starting to fail in four years but it will be so cheap to replace with a couple of terrabytes whats the point in worrying. I'd probably wait to but them i'm decidedly cheap. The long term problem i see with ssd is buying second hand, if you want a cheap drive for a linux box or what ever they may be difficult to come after a certain age.
     

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