Date: Tue, 14 Jul 2015 21:17:14 -0500 From: "Matthew D. Fuller" <fullermd@over-yonder.net> To: kpneal@pobox.com Cc: Pawel Jakub Dawidek <pjd@FreeBSD.org>, RW <rwmaillists@googlemail.com>, freebsd-geom@freebsd.org Subject: Re: RFC: Pass TRIM through GELI Message-ID: <20150715021714.GL96394@over-yonder.net> In-Reply-To: <20150714214813.GA65182@neutralgood.org> References: <20150324021924.GQ52331@over-yonder.net> <20150502125220.GS78376@over-yonder.net> <20150629013841.GO50491@over-yonder.net> <20150710200055.GB1270@garage.freebsd.pl> <20150710222837.GE96394@over-yonder.net> <20150711141553.3fcf91f4@gumby.homeunix.com> <20150713153146.GA1984@garage.freebsd.pl> <20150714064212.GZ96394@over-yonder.net> <20150714100936.GA1239@garage.freebsd.pl> <20150714214813.GA65182@neutralgood.org>
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On Tue, Jul 14, 2015 at 05:48:13PM -0400 I heard the voice of kpneal@pobox.com, and lo! it spake thus: > > Who says that a write to a logical block in an SSD will result in a > write to the same physical block? I thought it would typically or at > least frequently go to a different physical block. Wear levelling > and all that. Yes, it wouldn't be useful on a SSD (or a zvol, or any other backing that acts in a COW-ish way). And it's meaningless combining TRIM and shredding on a traditional platter drive, since it wouldn't do the TRIM part. Still, there can be some situations that would be both directly overwriting, and supporting unused-space-notifications; some virtualized SAN setups for instance, or or a md/VM/etc block device that supported sparse usage. -- Matthew Fuller (MF4839) | fullermd@over-yonder.net Systems/Network Administrator | http://www.over-yonder.net/~fullermd/ On the Internet, nobody can hear you scream.
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