From owner-freebsd-fs@freebsd.org  Wed Sep  9 10:41:12 2015
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Subject: Re: TRIM support (same bug as linux?)
To: freebsd-fs@freebsd.org
References: <CAD=tpedAx2XLtQe6Nn+HvXWZ0X=TekmkpTruxCndYqpBXPFaFA@mail.gmail.com>
From: Jan Bramkamp <crest@rlwinm.de>
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Date: Wed, 9 Sep 2015 12:41:08 +0200
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On 09/09/15 01:15, FF wrote:
> I'm asking a pretty vague question and I apologize in advance, not trying
> to troll.
>
> The question has to do with whether FreeBSD is using TRIM the same way as
> recent Linux kernels.
>
> https://blog.algolia.com/when-solid-state-drives-are-not-that-solid/ seems
> to imply that there are instabilities that can occur. Trying to avoid
> duplicating effort if this has already been addressed or if its a complete
> dead alley because there isn't a commonality.

At first the leading theory was that Linux triggered a firmware bug in 
the SSDs or that a bug in the handling of queued TRIM operations is 
responsible. The real culprit was a bug in the code for linear mdraid 
volumes causing the wrong blocks to be unmapped with TRIM.