Re: FFSv2 log option with SD card

[Sad Clouds <cryintothebluesky%gmail.com@localhost>]

On Sat, 22 Feb 2020 11:43:42 +0100
tlaronde%polynum.com@localhost wrote:

> On Sat, Feb 22, 2020 at 08:24:18AM +0000, Sad Clouds wrote:
> > On Sat, 22 Feb 2020 11:37:35 +1100
> > MJ <mafsys1234%gmail.com@localhost> wrote:
> > 
> > > 
> > > On 22/02/2020 4:28 am, Sad Clouds wrote:
> > > > Hi, is it advisable to NOT enable log option for FFSv2 that
> > > > resides on SD card due to flash memory wearing out in those
> > > > regions, or does it make no practical difference because of
> > > > built-in wear levelling?
> > > 
> > > 
> > > How long's a piece of string?
> > > 
> > > Wear levelling just evens out the wear... surprise. It doesn't
> > > account for the overall wear.
> > 
> > Well the SD card contains a general purpose file system, so I'm
> > expecting some wear on it as data is written over time (normal
> > desktop computer use). I wasn't sure if FFSv2 logging would
> > significantly shorten the life span. But I'm guessing it may not be
> > such a big issue for quite a few years.
> 
> From what I have gathered from infos taken here and there, it will
> depend on how much percentage the data is occupying on the SD card. If
> there is enough empty room on the SD card, the card is optimized so
> that new data is written "elsewhere" so that new writes impact other
> sectors. The much you have not used sectors, the less the sectors are
> overwritten and thus the longer the card will survive.
> 
> The error is taking a card that is too small and fits too closely the
> amount of data being retained.

Not sure how this would work. If the card is brand new, then I guess it
knows the memory cell is empty, but once you have filled the card and
then deleted most of the files, file system will mark those blocks of
data as free, but the card doesn't know the data has been deleted. I
don't think there is anything like TRIM command.