Re: [gentoo-user] SSD discard / fstrim

[Rich Freeman]

On Thu, Sep 4, 2014 at 2:26 PM, Сергей <protserovsd@×××××.com> wrote:
> You need to run Fstrim if you mounted your partition WITHOUT "discard"
> option and did lots of changes. For example, if you installed your
> system without "discard", do fstrim and then add "discard" to
> /etc/fstab.
>

Just a note that depending on the SSD model, discard can have a
substantial performance penalty with negligible benefit compared to
just sticking fstrim in your crontab.

In theory the ssd should just handle discard by making a note of what
is trimmed and utlizing this information when needed.  In practice
many ssds handle a trim by dropping whatever they're doing and don't a
copy/delete cycle if only part of a block is trimmed, which defeats
the whole point of trimming in the first place.  FStrim has the
advantage of being more asynchronous and possibly being able to
consolidate trims over a longer time-period, which could improve
performance if the ssd isn't smart about it.

Is there a really good place to go for SSD reviews/etc that actually
takes this sort of thing into account?  After getting an SSD it became
apparently that they vary widely in terms of quality.  Heck, I can't
even tell you what the erase cycle count is from the SMART info, while
other models seems to provide all kinds of useful info.

--
Rich