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Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file

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On Monday, April 08, 2019 09:41:10 AM Alexander V. Makartsev wrote:
> There are NVMe drives and SSDs intended to be used in servers with high
> workloads like cache storage. These server grade drives must be rated
> for at least 3 DWPD (Drive Writes Per Day) or more.

Thanks!  I really hadn't encountered the acronym NVMe before.

Looking at some (e.g., by description "SAMSUNG 970 PRO M.2 2280 512GB PCIe 
Gen3. X4, NVMe 1.3 64L V-NAND 2-bit MLC Internal Solid State 
Drive (SSD) MZ-V7P512BW") seem to be the older style of SSD 
technology (V-NAND 2-bit MLC) which might be a little more 
reliable (though more expensive), than 

some others which use the 3-D NAND technology, which presumably has about the 
same longevity / reliability as devices labeled as SSDs which use the 3-D NAND 
technology -- so I guess I have to be careful in how I shop (which is always 
the case, anyway).

Two links, both in the same ballpark pricewise:

   * [[https://www.newegg.com/Product/Product.aspx?Item=N82E16820147693]
[SAMSUNG 970 PRO M.2 2280 512GB PCIe Gen3. X4, NVMe 1.3 64L V-NAND 2-bit MLC 
Internal Solid State Drive (SSD) MZ-V7P512BW]]

   * [[https://www.amazon.com/BLACK-SN750-NVMe-Internal-
Gaming/dp/B07M64QXMN?tag=pcworld02-20&psc=1&ascsubtag=US-001-2899351-000-1442373-
web-20][WD BLACK SN750 1TB NVMe Internal Gaming SSD - Gen3 PCIe, M.2 2280, 3D 
NAND - WDS100T3X0C]]

And thanks for the explanation / clarification on some of the terminology:

> This means, if you have a 500GB SSD rated for 3 DWPD and it has 5 year
> warranty, then you can safely write 1,5TB to it each day for next 5 years.
> That is 3 * 500 * ( 365 * 5 ) / 1000 = 2737TB in total. (TBW)
> 
> You can convert TBW to DWPD if you want.
> Let's say we have 240GB SSD rated for 768 TBW and it has 5 year warranty.
> That will be ( 768 * 1000 ) / ( 365 * 5 ) = 420GB could be written per
> day, or 420 / 240 = 1,75 DWPD
> 
> Let's say we have 256GB SSD rated for 300TBW and it has 5 year warranty.
> That will be ( 300 * 1000 ) / 1825 = 164GB could be written per day, or
> 164 / 256 =  0,64 DWPD
> 
> IMO, an average consumer grade SSD (preferably MLC NAND based, 240GB+, 5
> year warranty) should be rated at least 1 DWPD to be worth buying, so it
> could be used (without paying constant attention to it,
> implementing various tricks and restrictions to its workload, etc) for a
> very long period of time, extending far beyond its warranty period, if
> your workload is lower than 1 DWPD.
> However, in reality it is so much trouble just to find suitable device.
> This involves browsing through terribly designed manufacturer websites
> with dark marketing patterns [1] and a pile of specification datasheet
> files.
> Also keeping in mind how SSD manufacturers don't like to talk about this
> inconvenient topic for them, trying to hide TBW DWPD ratings by using
> MTBF ratings instead.
> 
> 
> 
> [1] https://darkpatterns.org/

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Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-06 19:40 +0200
  Re: Measuring (or calculating) how many bytes are actually written to  disk when I repeatedly save a file "Alexander V. Makartsev" <avbetev@gmail.com> - 2019-04-06 22:40 +0200
  Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file Stefan Monnier <monnier@iro.umontreal.ca> - 2019-04-06 23:50 +0200
    Re: Measuring (or calculating) how many bytes are actually written to  disk when I repeatedly save a file Nicholas Geovanis <nickgeovanis@gmail.com> - 2019-04-07 00:40 +0200
    Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Curt <curty@free.fr> - 2019-04-07 11:50 +0200
      Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Curt <curty@free.fr> - 2019-04-07 12:00 +0200
      Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-07 15:10 +0200
    Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-07 14:20 +0200
      Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Erik Christiansen <dvalin@internode.on.net> - 2019-04-07 15:00 +0200
      Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file Stefan Monnier <monnier@iro.umontreal.ca> - 2019-04-07 18:30 +0200
  Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Andy Smith <andy@strugglers.net> - 2019-04-07 03:30 +0200
    Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-07 15:00 +0200
  Re: [OFF-LIST] Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-07 14:00 +0200
  Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Carles Pina i Estany <carles@pina.cat> - 2019-04-07 22:30 +0200
    Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Reco <recoverym4n@enotuniq.net> - 2019-04-07 22:30 +0200
      Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Curt <curty@free.fr> - 2019-04-08 09:50 +0200
        Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-08 14:50 +0200
          Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-08 15:40 +0200
          Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Curt <curty@free.fr> - 2019-04-08 15:40 +0200
            Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-08 15:50 +0200
              Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Curt <curty@free.fr> - 2019-04-08 16:20 +0200
                Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-08 17:00 +0200
                Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file Gene Heskett <gheskett@shentel.net> - 2019-04-08 18:20 +0200
                Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Curt <curty@free.fr> - 2019-04-08 19:00 +0200
                Re: Measuring (or calculating) how many bytes are actually written to  disk when I repeatedly save a file "Alexander V. Makartsev" <avbetev@gmail.com> - 2019-04-08 19:20 +0200
            Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Andy Smith <andy@strugglers.net> - 2019-04-12 11:20 +0200
              Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Curt <curty@free.fr> - 2019-04-12 14:10 +0200
                Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-12 19:20 +0200
                Re: Measuring (or calculating) how many bytes are actually written  to disk when I repeatedly save a file Michael Stone <mstone@debian.org> - 2019-04-12 20:50 +0200
                Re: Measuring (or calculating) how many bytes are actually written to  disk when I repeatedly save a file "Alexander V. Makartsev" <avbetev@gmail.com> - 2019-04-12 22:50 +0200
          Re: Measuring (or calculating) how many bytes are actually written to  disk when I repeatedly save a file "Alexander V. Makartsev" <avbetev@gmail.com> - 2019-04-08 15:50 +0200
            Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-08 18:00 +0200
      Re: Measuring (or calculating) how many bytes are actually written to disk when I repeatedly save a file rhkramer@gmail.com - 2019-04-08 14:40 +0200
        Re: Measuring (or calculating) how many bytes are actually written to  disk when I repeatedly save a file David <bouncingcats@gmail.com> - 2019-04-08 16:40 +0200

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