Re: Does nilfs2 do any in-place writes?

[Mark Trumpold <markt-qk0wvQ0ghJwAvxtiuMwx3w@public.gmane.org>]

On 1/18/14 1:44 AM, "Clemens Eisserer" <linuxhippy-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

>Hi again,
>
>> Rather, the issue on the flash devices may come from the current
>> immature garbage collection algorithm.  The current cleanerd only
>> supports the timestamp-based GC policy which always tries to move the
>> oldest segment first and even moves segments full of live blocks,
>> thereby shortens the lifetime of flash devices. :-(
>
>It depends - for SSDs the timestamp policy is not optimal as it leads
>to unnecessary writes.
>
>On the other hand, most cards only implement dynamic wear leveling
>(wear leveling takes only place for areas that are written to, which
>leads to very uneven wear distribution when there is mostly static
>data) and also don't have read-disturb handling.
>So for cards it is actually helpful to have the writes spread out
>evenly and as a bonus there is no need to worry about read-disturb
>effects =)
>
>Regards, Clemens
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Hi Clemens and group,

Good information.  So, is it true that the logging/cow nature of
nilfs actually improves wear leveling by having 'writes spread out
evenly'?

Regards,
Mark T.
>


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