Date: Wed, 20 Dec 2017 10:53:00 +0800 From: Erich Dollansky <freebsd.ed.lists@sumeritec.com> To: RW via freebsd-questions <freebsd-questions@freebsd.org> Cc: RW <rwmaillists@googlemail.com> Subject: Re: hd firecuda Message-ID: <20171220105300.1497c3a9.freebsd.ed.lists@sumeritec.com> In-Reply-To: <20171219144606.0217ee55@gumby.homeunix.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>
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Hi, On Tue, 19 Dec 2017 14:46:06 +0000 RW via freebsd-questions <freebsd-questions@freebsd.org> wrote: > On Tue, 19 Dec 2017 08:14:18 +0800 > Erich Dollansky wrote: > > > The drives can now use a reserved space of the disk to store the > > data. 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? > > > It could be also that > > the disk fills first SSD and then the reserved space. > > If that happened I'd expect the speed to first drop to an intermediate > speed of 50-100 MB/s, where the the non-shingled area is being written > to, and then drop again when the non-shingled area fills. > > 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. I first thought that the first drive is faulty. But the second shows the same behaviour. Since these things are finished, the drive behaves basically like an SSD. Erich > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org"
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