Date: Wed, 20 Dec 2017 14:13:32 +0000 From: RW <rwmaillists@googlemail.com> To: freebsd-questions@freebsd.org Subject: Re: hd firecuda Message-ID: <20171220141332.3fa53ab5@gumby.homeunix.com> In-Reply-To: <20171220105300.1497c3a9.freebsd.ed.lists@sumeritec.com> References: <1513447749.62024.1.camel@yandex.com> <20171217112428.150d8041.freebsd.ed.lists@sumeritec.com> <20171217111319.6a1af590@gumby.homeunix.com> <20171217194753.3ab59e6d.freebsd.ed.lists@sumeritec.com> <20171217150007.642efc20@gumby.homeunix.com> <20171218085219.2fec7c3b.freebsd.ed.lists@sumeritec.com> <20171218162625.5bcc543e@gumby.homeunix.com> <20171219081418.5672730b.freebsd.ed.lists@sumeritec.com> <20171219144606.0217ee55@gumby.homeunix.com> <20171220105300.1497c3a9.freebsd.ed.lists@sumeritec.com>
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On Wed, 20 Dec 2017 10:53:00 +0800 Erich Dollansky wrote: > Hi, > > On Tue, 19 Dec 2017 14:46:06 +0000 > RW via freebsd-questions <freebsd-questions@freebsd.org> wrote: . On long writes, this space will also be filled. > > > > It's unlikely that it would fall back to discarding useful cache in > > the SSD *after* filling the larger non-shingled area of the drive. > > If that bit of extra buffering made a useful difference they'd just > > increase the size of the non-shingled area. > > how to increase the non-shingled area without shrinking the drive's > available size? They'd design it with the right size in the first place using their experience with ordinary shingled drives. > > IMO what you are seeing is consistent with selective read caching > > plus write caching into the non-shingled area. > > How do you explain then the deep breath? What do I call a deep breath? > An access which takes more than a minute. It only happens when huge > amounts of data is written to the drive like updating sources and > ports tree and then starting to compile them. Any explanation you have involving buffering writes through flash also fits buffering through the non-shingled area.
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