Date: Sun, 3 Nov 2013 09:03:23 +0000 From: symbolics@gmx.com To: Warren Block <wblock@wonkity.com> Cc: geom@freebsd.org, hackers@freebsd.org Subject: Re: GEOM mentor request Message-ID: <20131103090323.GA1744@lemon> In-Reply-To: <alpine.BSF.2.00.1311011310340.23437@wonkity.com> References: <20131101103158.GA35397@lemon> <alpine.BSF.2.00.1311011310340.23437@wonkity.com>
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On Fri, Nov 01, 2013 at 01:23:12PM -0600, Warren Block wrote: > On Fri, 1 Nov 2013, symbolics@gmx.com wrote: > > > + Implement new things. Some ideas I have had: > > + GEOM "ERASE" - Rewrite deletes into random writes. > > + GEOM "PLUG" - Persistent version of the connect/disconnect verbs > > where the flag sits in the class metadata. This might be a cleaner > > approach, rather than adding the verbs to all the existing > > providers. > > + GEOM "TAP" - Allow userspace processes to hook into the GEOM > > API. Intended for debugging and development. > > + GEOM "WCACHE" - Allow you to use small, fast provider as a buffer > > for a larger, slower provider. > > + GEOM DTrace provider. Provide GEOM specific probes to complement > > the IO provider. > > + Probably other bits I can't remember right now. > > How about an explicit geom retaste command? "true > /dev/ada0" is > misleading to the reader. Yes, that would be good. It's on my list. > Also, a RAM-cached version of gmirror that would report writes finished > as soon as the faster drive finishes. Kind of the opposite of the > WCACHE above. This would permit creating mirrors of an SSD and hard > drive without performance loss, at least up until available write > buffer space runs out. This one may not be so easy. I can see the benefit. This would be like a mirror with a journal. As long as it has a different name from mirror, 'lazy mirror' ?, I think it would be interesting. The only concern I have would be that some users could use it and assume the normal mirror semantics, e.g. that all discs are equally redundant, which wouldn't be true. --sym
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