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




On Friday, April 12, 2019 08:07:07 AM Curt wrote:
> On 2019-04-12, Andy Smith <andy@xxxxxxxxxxxxxx> wrote:
> > Honestly my advice to the OP as suggested what seems like many days
> > ago remains: just take a measure, do a day or two of work, take
> > another measure, check the difference in byte count and extrapolate
> > from there. I'd be amazed if you didn't end up with multiple decades
> > of write headroom.
> 
> No need to even measure.
> 
> https://en.wikipedia.org/wiki/Solid-state_drive#SSD_reliability_and_failure
> _modes
> 
>  Device age, measured by days in use, is the main factor in SSD
>  reliability, and not amount of data read or written, which are measured
>  by TBW or DWPD.
> 
> http://0b4af6cdc2f0c5998459-c0245c5c937c5dedcca3f1764ecc9b2f.r43.cf2.rackcd
> n.com/23105-fast16-papers-schroeder.pdf

I read (or skimmed) these the first time you posted them (well, the first one 
might have been a different URL with similar information).  

Unless I missed something, neither one of them addresses 3-D NAND drives, 
which presumably would not do as well.  (Well, they might exceed their 
published TBW figures, but those figures are, iirc, lower than those for SLC or 
MLC).

It looks like I am writing something like 20 GB per day, or something like 8 
TB per year (due to my quick trigger on <ctrl>s).  I plan to test over a 
longer period of time -- right now I am doing a little less writing due to tax 
season.